The look on the dude's face when he busted was fun! That explosive look turning to surprise and relief like a normal nut-bust orgasm, but mixed together with short periods of a driver's strained attention to the road ahead.
That's exactly what I have in the car, ready to shoot my load into so there's no mess. I pull over somewhere where I can pull down my pants and go all the way in a sticky full body orgasm just concentrating on my dick and the unbelievable pleasure. Doing it while driving would be too dangerous with all that going on, then wiping my penis.