I saw the free NRMA membership deals and that prompted me to check out what benefits I get with RACT. They had the usual 'show your card at participating United Petroleum sites and save 6¢ per litre' but then I noticed they have an extra 6¢ discount on top of the regular one at 4 unmanned sites around the state. Here's an excerpt taken from the linked web page:
Currently the unmanned sites at New Norfolk, Legana, Sheffield and Exeter offer an extra 6 cents discount after hours between 6pm - 6am. The main fuel price board will display this discounted price between these times. Additionally, if you use your RACT membership card, the fuel price on your receipt will include the RACT discount as well as the after hours discount. This equates to a total discount of 12 cents.
RACT memberships start at $39.00/yr for Lifestyle.
A comment by mrWLSN below suggests this may be applicable at other sites than the ones named by RACT, so I've changed the title of the post to reflect that.