She starts the engine... rev's it a few times... then turns the car off? WTF?
That's not right... If she doesn't want sex... then she doesn't need to get your motor revving.. Women can lose arousal like they change clothes... it's not quite so easy for men... and she needs to understand this. To do so to a man is bordering on cruelty.
Decide how far you think she should be able to go... then decide how much is too far... and let her know these boundaries... Talk with her and let her know that if she pushes you to this point, then you're going to really, really want sex. If she doesn't want sex at the time, then she doesn't need to get you to that point... plain and simple.
Nothing wrong with her not wanting sex... that's her prerogative... but it is cruel to tease you and can lead to unnecessary frustrations and even resentment.
"The weakest soul, knowing its own weakness, and believing this truth that strength can only be developed by effort and practice, will, thus believing, at once begin to exert itself, and, adding effort to effort, patience to patience, and strength to strength, will never cease to develop, and will at last grow divinely strong."
- James Allen