Speeding trucks: Driving faster than 100km/h: Truth or Myth

Vote for Pedro on 22/06/2019 - 10:34
Last edited 23/06/2019 - 19:31

We know trucks are limited to 100km/h and some (not sure if all) have speed limiters. We’ve all probably also experienced driving the speed limit on a freeway and being overtaken by a truck.

What is the experience of OzBargain members and thoughts.

Dashcam evidence links encouraged :-)

Ps. Just because it’s downhill, it's still speeding.

Update: Speed check using Waze

M5 run between Fairford Rd and Hume Hwy Liverpool both directions. Was able to reasonably sit speedo on 100. Waze showed mostly 98 with the occasional dip to 97 with a quick return to 98.

Not scientific as it relies on me judging the 100 speedo mark and other variables but gotta love Toyota. 2% is fair.

Poll Options expired

  • 257
    Happens all the time
  • 14
    I’ve seen it occasionally
  • 12
    Doesn’t happen!
Automotive

Comments

  • Peter Enis on 22/06/2019 - 10:50
    +25

    Don't go by your cars speedo as you'll likely be going closer to 90 than 100, and of course trucks will be constantly overtaking. Use Waze to know your true speed. Last 3 cars I've driven, show 106 on the speedo to be going 100.

    • Vote for Pedro on 22/06/2019 - 10:52
      +3

      The speedo is pretty much what us average folk use to judge our speed.

      • Peter Enis on 22/06/2019 - 11:02
        +16

        You only need to work it out once for your car then you can just drive accordingly.
        You might suddenly find no more trucks overtaking you.

        • Vote for Pedro on 22/06/2019 - 11:06
          +10

          Or perhaps the Australian Standard for margin of error for speedos should be tightened so that people can rely on the device designed and intended to provide them with speed information. Just a thought.

          Ps. I’ll give the gps thing a go though :-)

          • afoveht on 22/06/2019 - 14:49
            +24

            @Vote for Pedro: Make sure you get new factory spec'd tyres every week.

            • Vote for Pedro on 22/06/2019 - 14:56
              +1

              @afoveht: Did an amateur sleuth test earlier today. 2% off according to waze. Speedo showing 100 while waze showed 98.

              Car is 4 yrs old. 50000km and original tyres. Pressure checked last Sunday and were to spec.

                • RSmith on 23/06/2019 - 08:56
                  +4

                  @payless69:

                  who are the best drivers in the world in their industry

                  Isn't everything in Australia best in the world?

                • Vote for Pedro on 23/06/2019 - 09:17
                  +3

                  @payless69: What I do is pay Toyota every 6 months to do that for me. It’s unfair that you accuse them of not doing their job diligently.

              • Thepizzawhisperer on 23/06/2019 - 09:37
                +1

                @Vote for Pedro: Your original tyres with 50000km won't be to spec size any more. The smaller worn out Tyre reduces the circumference slightly, so the speedo thinks you are traveling faster than you actually are.

                • Vote for Pedro on 23/06/2019 - 10:14
                  +2

                  @Thepizzawhisperer: Except i did a bush scientist experiment and it showed 2% error. When speedo sitting on 100, waze showed 98. And yes, next time I’m on m5 I’ll do it the other way around too.

                  • digitalbargain on 24/06/2019 - 22:06
                    +1

                    @Vote for Pedro: Your science is wrong.. question is how many white lines crossed in 10 seconds.. scientific approach is to record on dashcam.. then measure distance between each white line and the distance between the lanes are Pythagoras pi to the power of 7.. however this only holds true in bad raining weather.. if the weather is bad it's 100% accurate at least 9% of the time

          • spaceflight on 22/06/2019 - 23:56
            +1

            @Vote for Pedro:

            Or perhaps the Australian Standard for margin of error for speedos

            They are tight.
            The speedo must always read 'safe', meaning the vehicle must not travel faster than the speed indicated by the speedo.

            Building a Speedo that's 100% accurate from the factory means there is a high chance of it reading 'unsafe' over time so it's better to have them read 'safe'.

            We know that speed kills so if you're only going 90 when you think you are going 100 is that a bad thing?

            The Australian standards align to European ones.

            • Vote for Pedro on 23/06/2019 - 09:38
              +1

              @spaceflight: if we can get trucks, cars and trains to be autonomous we surely should be able to do a little better with speedo accuracy than 14%.

              • spaceflight on 23/06/2019 - 10:23

                @Vote for Pedro:

                surely should be able to do a little better with speedo accuracy than 14%.

                Speedo accuracy is based on a number of variables that change from car to car.

                Even the amount of air and wear on your tyres can impact the indicated versus actual speed.
                If you get new tyres or wheels that are a different size to the factory ones then the indicated versus actual speed will change again.

                Building a 100% accurate Speedo only means that it will not be accurate as things in the car wear and change.

                • Vote for Pedro on 23/06/2019 - 10:25

                  @spaceflight: So much for self drive or semi autonomous cars if we can’t do a little better than 14%

                  • spaceflight on 23/06/2019 - 10:40

                    @Vote for Pedro: You don't need a 100% accurate Speedo for self driving or autonomous cars.

                    Plus current Speedos (which are mechanically calculated) reliably more accurate than other methods such as GPS which are subject to external influence.

                    • Vote for Pedro on 23/06/2019 - 10:55
                      +1

                      @spaceflight: Geez, and there i was earlier getting slammed for not using gps to measure my speed and relying on the speedo. Which one is it.

                      But seriously, I get all the variables and how difficult it all can be, but 14% is just ridiculous imo. Surely we can do a bit better. Maybe 8%. And yes, it’s just my opinion - no science behind it.

                      • spaceflight on 23/06/2019 - 11:16

                        @Vote for Pedro:

                        Which one is it.

                        It depends.

                        On a long straight road with clear visibility to the sky and where you are at a fixed speed your GPS is probably accurate.

                        On a winding road or any road where you are changing speed and still have clear visibility to the sky, GPS is going to be less likely to be accurate.

                        In a city where your speed is fluctuating a lot GPS is not going to give an accurate instantaneous speed reading.
                        And once you add in tall buildings that reflect and block GPS signals you get less reliability.

                        I get all the variables and how difficult it all can be, but 14% is just ridiculous imo. Surely we can do a bit better. Maybe 8%. And yes, it’s just my opinion - no science behind it.

                        I don't think you do. The simple ones are.

                        Tyre pressure can cause speedo differences of around 3%.
                        Going from an old to new tyre can cause a difference of 2-4%
                        Changing to a new profile tyre can give an 8% difference.

                        And those are just general observations. Plus they can all work together for example going from flat old tyres to correct pressure new tyres.

                        And I don't know why you think it is 14%, that is not what the ADR says. It is only 14% for 100 km/h (which is not actually 14% but the calculated error percentage)

                        • Vote for Pedro on 23/06/2019 - 11:21
                          -2

                          @spaceflight: I guess it’s all just too hard. We should give up and never try to get better?

                          • spaceflight on 23/06/2019 - 11:30

                            @Vote for Pedro: I don't think you understand. We can build an accurate speedo it isn't hard. Keeping it accurate is

                            Speedos are 'inaccurate' by design so that people are not going faster than indicated with an allowance for things on a car that can change. It also means they do not need to be regularly calibrated.

                            If you want your speedo to be more accurate pay to get it calibrated every month.

                            • Vote for Pedro on 23/06/2019 - 11:34
                              +1

                              @spaceflight: I don’t. But that’s where the ‘your speedo is wrong that’s why you think truckies are speeding’ argument comes from.

                              It’s a good distraction defence.

                  • brendanm on 23/06/2019 - 10:59

                    @Vote for Pedro: Where are you getting 14% from?

                    • Vote for Pedro on 23/06/2019 - 11:08

                      @brendanm: https://www.ozbargain.com.au/node/465582#comment-7420689

                      At 100km/h the acceptable error 14%. That is 10% +4km/h

                      “For a vehicle travelling at a true speed of 100km/h, the speedo must read between 100km/h and 114km/h. The effect of this is that many drivers will find that at 100km/h they are driving up to 14km/h below the speed limit if they rely on the vehicle’s speedo.”

                      • brendanm on 23/06/2019 - 11:09
                        -2

                        @Vote for Pedro: 10% + 4kmh is not 14%. It's 10% + 4kmh. At 80 the result will be different to the result at 130.

                        • Vote for Pedro on 23/06/2019 - 11:11

                          @brendanm: Yes apologies should have indicated that it was in relation to the topic of 100km/h

                          • brendanm on 23/06/2019 - 11:13

                            @Vote for Pedro: Or just say 10% +4. Isn't it common knowledge that most speedos read well under anyway? Can you imagine the whining if people got pinged by speed cameras because speedos were allowed to under read.

                            • Vote for Pedro on 23/06/2019 - 11:23

                              @brendanm: Again this topic is about the perception of truck drivers speeding over the 100 speed limiter. A speedo reading plays a part in that perception.

                              • brendanm on 23/06/2019 - 16:22
                                +2

                                @Vote for Pedro: Of course it does, and it's not truckies faults that people don't understand that their speedometers are far from accurate. Same as the morons that sit 10kmh under the limit in the right hand lane.

                • Boshait on 23/06/2019 - 13:47

                  @spaceflight: Why not use doppler ground radar instead of antiquated mechanical method?

                  • spaceflight on 23/06/2019 - 14:25

                    @Boshait: Ignoring cost, computational power and all other issues.

                    What is the use of knowing how high off the ground your car is? Because that's what you are going to get by pointing a Doppler Radar at the ground.

                    Just because mechanical Speedos are old doesn't mean there is magically a new, better, more efficient and most importantly reliably accurate method.

              • [Deactivated] on 24/06/2019 - 16:03
                +2

                @Vote for Pedro: I wonder if eventually all vehicles will have a builtin GPS and it will be used to re-calibrate the speedo when required.

                • spaceflight on 24/06/2019 - 19:16

                  @[Deactivated]: Unlikely.

                  Why rely on something that you can't control for something so important?

                  Plus the accuracy of GPS depends on a number of external factors and how and where you are driving.

                  • [Deactivated] on 24/06/2019 - 19:42

                    @spaceflight: But the accuracy of GPS is always known. If the error is to great then obviously you postpone the calibration for later. It is much better than the current practice of calibrating once in the factory and never again.

                    • spaceflight on 24/06/2019 - 23:57
                      +1

                      @[Deactivated]: So you want to rely on something that's only accurate to metres to determine your speed?

                      The accuracy confidence of GPS is known, the actual accuracy to an exact location isn't.

                      The average speed of city traffic is about 20km/h, that's 5.6m per second.

                      The sort of GPS you would put in a car is accurate to about 5m.

                      If you check GPS speed every second at second 1 you were -5m accuracy and at second 2 you were at +5m accuracy, the car has also moved 5.6m. How fast had the car traveled in those 2 seconds?
                      You have 'traveled' 15.6m so your speed is calculated as nearly 60km/h

                      And that's only one axis of travel. GPS can do both horizontal and vertical so you have 2 axis of error that can come into your speed calculation.

                      How do you reliably calculate speed in a city when you have poor visibility of the sky?

                      GPS is not good at a reliable instant speed reading, your car speedo is.

                      You might end up 'calibrating' your speedo to read slow so you are always speeding.

                      The biggest change the average person will see in their car speedo is about a 3% decrease (reading slower than actual) as their tyres wear. GPS calibration could give errors much higher than this.

                      • coin saver on 25/06/2019 - 07:11

                        @spaceflight: Also with GPS the display is not real time. (there is a delay from taking the reading to receiving the reading)

                      • [Deactivated] on 26/06/2019 - 19:57

                        @spaceflight: How accurate is GPS for speed measurement?

                        As with positioning, the speed accuracy of GPS depends on many factors.

                        The government provides the GPS signal in space with a global average user range rate error (URRE) of ≤0.006 m/sec over any 3-second interval, with 95% probability.

                        This measure must be combined with other factors outside the government's control, including satellite geometry, signal blockage, atmospheric conditions, and receiver design features/quality, to calculate a particular receiver's speed accuracy.

                        https://www.gps.gov/systems/gps/performance/accuracy/

                        Also

                        I wasn't suggesting the vehicle calibrates the speedo continuously. It could be restricted to specific conditions like motorways driving at a steady speed when GPS signal is of sufficient accuracy etc.

                        • spaceflight on 26/06/2019 - 21:07

                          @[Deactivated]: You have quoted something for the GPS network, not a GPS receiver.

                          User equivalent range error refers to the error of a component in the distance from receiver to a satellite. So UERE is the umbrella term for these error sources below

                          Satellite clock
                          Upper atmosphere
                          Receiver clock
                          Satellite orbit
                          Lower atmosphere
                          Multipath

                          The GPS in your phone/car is not accurate to ≤0.006 m/sec over any 3-second interval

                          • [Deactivated] on 27/06/2019 - 22:37

                            @spaceflight: Like I mentioned in the first comment, hopefully eventually vehicles will self calibrate. So I a, not talking about current practices.

                            • spaceflight on 27/06/2019 - 22:48

                              @[Deactivated]: But why would you want to calibrate your speedo to an external source with a number of variables that you can't control?

                              The way speedos work the only variable to change them significantly is buy changing the tyre size which most people don't do.

                              Plus current speedos will never underestimate your speed. Calibrating to an external source could lead to this.

                              • Euphemistic on 28/06/2019 - 06:47

                                @spaceflight: End of the day it doesn’t need to be that accurate. Road conditions vary so much it doesn’t matter if you aren’t doing exactly the speed limit all the time.

                                We all think we have a right to drive at exactly the number in the circle because we’ve been brainwashed by years of advertising that exceeding it will kill us.

            • afoveht on 23/06/2019 - 10:09
              +3

              @spaceflight:

              The Australian standards align to European ones.

              But Australian drivers and roads don't - there's the biggest problem.

            • bmerigan on 24/06/2019 - 23:10

              @spaceflight: I'm assuming some tongue-in-cheek there

              • spaceflight on 24/06/2019 - 23:22

                @bmerigan: No. Why?

                • bmerigan on 24/06/2019 - 23:23

                  @spaceflight: Oh, well, I chuckled when you mentioned how we all know that speed kills.

                  • spaceflight on 24/06/2019 - 23:24

                    @bmerigan: That's because it does. I don't know why it's funny.

                    • bmerigan on 24/06/2019 - 23:28

                      @spaceflight: Speed is fine. Crashing kills. And the causes of crashes are usually not speed related.
                      The only concession I give on your statement is that more damage is done if a crash occurs at higher speed. But we should be reducing the number of crashes, not just making them less severe.

                      • spaceflight on 25/06/2019 - 00:01

                        @bmerigan: Crashing is an outcome, not a variable.

                        In two identical crashes except for speed, the crash where speed was higher will have worse outcomes for everyone involved.

        • Musing Outloud on 23/06/2019 - 12:48

          Erm, depends on how your tyre pressure and tyre wear varies over time and cold to warm seasons.

          I get 3 to 4 km/hr variance over tyre life and summer to winter & if I've used a dodgy petrol station's dodgily calibrated tyre pump.

          So ongoing measurement using a phone app like waze, or other apps, is better.

      • pegaxs on 22/06/2019 - 11:07
        +12

        And I am trying to tell you, the average car speedo is inaccurate. By ADR standards, car speedos are allowed to read with an error margin up to 10% faster than what the car is actually going (but never lower than what the car is going). So, you could easily be "reading" 100km/h and you car could be doing anywhere from 90~100km/h.

        I have also explained "here" why is may seem like you are being passed by trucks. Trucks don't just use the wheels touching the road to measure speed, they use math. The ECU contains the data of the engine revs, the gearbox type, final drive type and tyre size to calculate speed. Some of the newer trucks even use other sensors, such as GPS. All of this data is cross-referenced to allow to ECU to make a much more acurate reading of your actual speed in a truck.

        Trucks need to calculate their speed as close as possible to the max they are allowed to run at because they need to make the best use of it. Cars, however, don't. Close enough is good enough for Mary Jo and her kids on their way to school to down to mum's for the weekend.

        I guess, your confusion also comes from what you perceive to be a truck and what vehicles are required to have a speed limiter on them. You may be dumping in all the sub 4.5GVM pantech and light commercial vehicles into the same barrel as B-double and road trains.

        • Vote for Pedro on 22/06/2019 - 11:09
          -5

          See my RACQ link below. Yes. Breath. Relax. zen.

          • pegaxs on 22/06/2019 - 11:11

            @Vote for Pedro: Cheers, glad you found it. I didn't see you had posted that until I had hit the reply button. Saves me a tonne of work trying to find the relevant ADR rules for speedo accuracy on cars.

            • Vote for Pedro on 22/06/2019 - 11:13

              @pegaxs: Does the same standard of error apply to trucks and is the speed limiter based on the speedo?

              • pegaxs on 22/06/2019 - 11:25
                -3

                @Vote for Pedro: Yes. The same ADR covers cars, trucks, motorcycles. The ADR says it can read with an error of up to 10%, but never lower than what actual speed the vehicle is doing. The ADR does NOT say that is HAS to indicate the error, just that it has an allowance of up to 10%.

                From the relevant ADR (18/00):

                8.5.1.1.2. indicate the actual vehicle speed, for all speeds above 40 km/h, to an accuracy of ± 10 percent

                • Euphemistic on 22/06/2019 - 17:22

                  @pegaxs: That quote contradicts what you are saying. All speeds above 40 accuracy plus or minus 10%. Or was it a typo? I know you meant error of 0% to +10%.

                  • pegaxs on 23/06/2019 - 00:21

                    @Euphemistic: I was lazy and going over old info from some old ADR forms we had on file. Turns out they need to be updated anyway. I just got and pasted what the PDF said. But being from 2006, it does seem odd that it says +/-

                    See the post I made below after updating my knowledge (thanks to @spaceflight) and sending a copy of the newer ADR 18/03 to work. We only had 18/00 at work. It’s still relevant, just not for cars made after 2006…

                    • spaceflight on 23/06/2019 - 10:56

                      @pegaxs:

                      it does seem odd that it says +/-

                      ± is correct for pre 2006 cars, it used to be acceptable for cars to have a slower indicated vs actual.

                      This is why you generally shouldn't get a speeding fine until you are over 10% above the posted speed sign and if you do with a pre 2006 car you have a basis to fight the ticket.

                      We only had 18/00 at work. It’s still relevant, just not for cars made after 2006…

                      I don't know what your work is, but if you have ADR on file shouldn't you make sure they are current so you are testing cars to the correct rules?

                • spaceflight on 22/06/2019 - 23:59
                  +1

                  @pegaxs:

                  8.5.1.1.2. indicate the actual vehicle speed, for all speeds above 40 km/h, to an accuracy of ± 10 percent

                  That does not apply and had not applied for a long time.

                  From July 1 2006 a new standard began its phase in and by 1 July 2007 all new vehicles had to comply. The new standard requires that:

                  The speedo must not indicate a speed less than the vehicle’s true speed or a speed greater than the vehicle’s true speed by an amount more than 10 percent plus 4 km/h.

                  • pegaxs on 23/06/2019 - 00:06

                    @spaceflight: Good to know. Just for my own reference, got a link to the ADR that says that? Would like to have a read to update my knowledge.

                    Edit: Think I found it under ADR 18\03. (Where: V1 being “indicated”, V2 being “actual” speeds.)

                    5.3
                    The speed indicated shall not be less than the true speed of the vehicle. At the test speeds specified in paragraph 5.2.5. above, there shall be the following relationship between the speed displayed (V1 ) and the true speed (V2).
                    0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h

                    And…

                    Annex 3.
                    In the case of vehicles of categories M and N: 0 ≤ (V1 – V2) ≤ 0.1 V2 + 6 km/h; (cars, busses and trucks)
                    In the case of vehicles of categories L3, L4 and L5: 0 ≤ (V1 – V2) ≤ 0.1 V2 + 8 km/h; (motorcycles and trikes)
                    In the case of vehicles of categories L1 and L2: 0 ≤ (V1 – V2) ≤ 0.1 V2 + 4 km/h. (Mopeds and scooters)

                    So, an example would be V1 = 120, V2 = 117.
                    0 ≤ (120 – 117) ≤ 0.1 117 + 6 km/h
                    0 ≤ (3) ≤ 11.7 + 6 km/h (pass)

                    V1 = 120, V2 = 102
                    0 ≤ (18) ≤ 10.2 + 6 km/h (fail)

                    V1 = 120, V2 = 124
                    0 ≤ (-4) ≤ 12.4 + 6 km/h (fail)

        • WreckTangle on 22/06/2019 - 11:12
          +1

          Yeah, i’ve noticed in the carpark that Mary Jo is always dropping her kids off late to school

        • dcep on 22/06/2019 - 13:54

          does speed camera or speed gun has 10% leeway ?

        • macrocephalic on 22/06/2019 - 18:54

          All of those are irrelevant as the tyre contacting the road is the final link in the chain, and it's the only one with any variability. If you mean that they take the speed off the drive shaft rather than at the wheel, then that's pretty common in all vehicles, my last motorcycle did that, but it's still effected by the tyre size.

          There are really only three ways to measure speed, wheel rotations, GPS, or with a sensor which actually measures the passing of the ground under the vehicle. I haven't heard of any vehicles which use the last one, but it should be possible.

        • bmerigan on 24/06/2019 - 23:15

          Surely truck speed is calculated the same as car speed, abides by the same ADR, and can be equally inaccurate.
          Unless, of course, there's a way for the truck driver to type his tyre diameter into the ECU before each trip.

          • pegaxs on 25/06/2019 - 00:03

            @bmerigan: Trucks are subject to the same ADR, but this just gives it a rule that says speedos can’t read under, and it can’t read out any more than 10% +4km/h. It doesn’t say it has to be out, just what the maximum amout of error is permissible.

            Yes, truck speedo can be inaccurate, but most long haul and freight trucks are set up to be as accurate as possible. If the law says they are allowed to do 100 and they are only doing 93, that is a huge slab of time in a trip from Brisbane to Melbourne. So trucks are usually tweaked to be right at their allowable max.

            ie: Brisbane to Melbourne = 1,782 km.
            @100km/h, that’s 17h49m
            @93km/h, that’s 19h10m.
            A 7km/h difference in speed limiter makes the same journey 1h20m longer. And time is money in freight.

            From what I understand is that the setting is based on brand new tyre rolling circumference. As the tyres wear, their rolling circumference is reduced, therefore the speed is less than indicated. It is most accurate at the time of brand new tyres and correct inflation.

            All that being said, I don’t play with speed limiter settings. I leave that to the guy at work who sets them up all the time. I’ve watched him do it, but I most definitely do not touch them.

      • DazMon on 22/06/2019 - 11:32

        i thought average folk used GPS as a better indicator of true speed?

        • Vote for Pedro on 22/06/2019 - 13:51
          +5

          I’m willing to place a bet that at least 85% of drivers use the speedo as their sole indicator of vehicle speed.

        • coin saver on 22/06/2019 - 15:40
          +2

          GPS in a lot of cases is no more accurate than a car speedo.

          • pegaxs on 22/06/2019 - 18:22
            +2

            @coin saver: This is right. GPS is good, just not as accurate as people think. It’s great on long, straight roads, not so good at slow, twisting roads.

            We have a GPS speed tester at work, and the list of things that has to be adhered to to get an accurate reading it’s more than just “put your phone in a holder and drive”

            • Musing Outloud on 23/06/2019 - 13:17
              +1

              @pegaxs: Agree. Best method is to set your cruise control on a "flat", long, straight section of road to the correct baseline legal GPS speed you want.

              GPS's or GPS phone apps, might not use maths that takes into account altitude. So setting cruise on an incline or decline will cause under or over speeding respectively when you get back on the flat by a few km/her at highway speeds. Imagine a flattish triangle with the longest 90 degree side horizontal. Your GPS is calculating the flat horizontal speed represented by the longest 90 degree side. Your vehicle is actually traveling the hypotenuse. Then add some over-running and under-running of the engine & drive train and you have lots of variables.

              You may also see your GPS speed slow slightly at freeway speeds on bendy roads with the cruise on. By 1 or 2 km/hr. This comes from the way your differential works on bends.

              I've noted these variables on various cars I have owned or hired. The worst variance being a VW golf whose speedo read 100 when I was actually doing 90 km/hr.

      • Vote for Pedro on 22/06/2019 - 13:48
        -5

        Jeez, whoever negged this needs a hug.

      • [Deactivated] on 22/06/2019 - 18:50
        +10

        Well, if you're more average than the rest, you'd use the line counting method.

        I just count to 10 seconds and make sure I haven't crossed more than 24 lines because I'm like, "if each line is 40 feet and I multiply that by 0.308 for metric conversion, then I…"

        "Oh shit, a truck!"

    • Diji1 on 22/06/2019 - 11:34
      -7

      Use Waze to know your true speed

      Uh … isn't that way less accurate than your speedometer?

    • npc on 22/06/2019 - 16:24

      That's right, 106=100 on the most cars I've driven.

      • bmerigan on 24/06/2019 - 23:17

        My AU was 10% out. My FG is 2% out.

    • whooah1979 on 22/06/2019 - 18:46

      We do 110km/h and trucks are still overtaking us left and right.

      • gromit on 23/06/2019 - 13:10

        Then your speedo is probably way WAY out. I usually sit on 110 too, can't remember the last time a semi or b double passed me while sitting on 110. and I drive a lot from Canberra to Sydney and occasionally Sydney to Brisbane. Also remember light trucks don't count as they don't have limiters.

        • whooah1979 on 23/06/2019 - 18:45

          The thing happens when we drive rentals to QLD and the ACT. We hit the cruise control on Hume hwy just outside the city. The overnight express trucks kept tailgating until they got enough room to overtake.

    • ankor on 23/06/2019 - 01:11

      According to my google maps app, 60kph on my speedo is 63kph in the GPS. So I've actually had to slow down. :S

      • Vote for Pedro on 23/06/2019 - 13:19

        Is that a new feature on google maps? I know waze has it but not google maps

        • ProlapsedHeinous on 23/06/2019 - 20:49
          +1

          Yeah, i started to see it sometime this week on mine. Its nice to see new things being added like the mark parking spot and crowdsourcing the crash/speed camera locations

    • cille745 on 23/06/2019 - 21:47

      Don't forget manufacturers will intentionally fudge it for highway fuel economy figures as well

      • spaceflight on 23/06/2019 - 22:51

        Don't forget manufacturers will intentionally fudge it for highway fuel economy figures as well

        How does that help?

        Fuel economy is calculated using a dynamometer so the car's speedo is never used.

        • cille745 on 23/06/2019 - 22:54

          Whoops, didn't know they used a dyno for that, would still come across better in real world tests

          • spaceflight on 24/06/2019 - 19:17

            @cille745: No it won't.

            Your speedo isn't used to calculate your fuel economy.

            That is done using your odometer.

    • sid101 on 24/06/2019 - 21:12

      Google maps also now showing speed.

  • Ughhh on 22/06/2019 - 10:56
    +1

    100kmph on my speedo reads about 95/96kmph on my gps.

    If you're only judging by your (rather inaccurate) speedo, then every truck and car will appear to be speeding over 100kmph (if theyre really thing 100kmph).

    People who are actually going 100kmph will be complaining about you.

  • Vote for Pedro on 22/06/2019 - 10:57
    +1

    Also, just found this: https://www.racq.com.au/cars-and-driving/safety-on-the-road/…

    Unbelievable. Wow, just wow.

    “For a vehicle travelling at a true speed of 100km/h, the speedo must read between 100km/h and 114km/h. The effect of this is that many drivers will find that at 100km/h they are driving up to 14km/h below the speed limit if they rely on the vehicle’s speedo.”

    • Kangal on 22/06/2019 - 11:08

      Not sure if it applies to Heavy Vehicles, but it seems like it does so.

      Which means when a truckie is speeding past you and is actually going 100km/h, then on his speedometer it would read that he's actually going 114km/h and it would be capped beyond that point. So if someone asks a truckie and says "Have you been speeding", he would say "No" and lie, but actually wouldn't know he wasn't speeding. Although most are smart and would simply say "it's not possible to speed with this vehicle, sir".

      • Vote for Pedro on 22/06/2019 - 11:10

        Not sure if the speed limiter is based on the speedo. I’m assuming it is. Also assuming same standard applies. Don’t know enough.

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