Fill Up At Busy Stations
Note: there is no solid statistics or conclusive research to prove this information. We have been told this tip but have found no evidence to support it.
If you don't mind waiting 5 minutes when you go to fill your car up, then try to buy your fuel from a busy petrol station.
When a station is consistently busy it will require its underground tanks to be filled on a regular basis. Whereas stations that don't have as much custom will have fuel sitting in the tanks for longer periods which can reduce the quality of the fuel. This may lead to fuel which is less powerful and less economical.
Problems
You may have to sit and wait to fill you car up, which can use a small amount of petrol cancelling the potential benefits. If you're expecting to wait a while turn your engine off.
Further Information
If anybody has any further knowledge on this and perhaps more science to back it up we would love to hear from you. Until that time we can't put any solid weight behind it, still, if you are a hardcore saver then it may be something you want to do.