Never done it on my runaround as you've gotta have the key out of the ignistion to undo the fuckin cap anyway!

Know there are a few which don't need a key....

Sure when i was at a Shell garage last week filling up the taxi some bloke was getting a right bollocking off the petrol station attendant for having his BMW running while filling up...

The bloke then started shouting and rabbiting on about having the air-con on for his mother who was in the car...

Toff cunt!