We've done it twice in the ten years we've been together. Obviously it's a very risk sexual activity, since there's the risk of the driver suddenly accelerating, braking, or simply losing control of the vehicle!
Too dangerous, though I do admit that my husband and I were stupid enough to have done it once many, many years ago when we were a new couple -- and obviously young and dumb. We were driving back home across the flat open countryside of the state of Kansas and I guess the monotony, flat plains, and wide open road made us bored. Thankfully, there were no bad consequences. We'll certainly never try that again!
Been a really long time since anything like that since we have children and they are almost always with us. When they aren't with us we are going somewhere with a purpose and no time to play. Oddly enough I teased him about doing it just the other day cuz we were driving to pick up our car from the service center. Didn't happen though - timing and all that.
Course it really isn't a very responsible act but still...
We haven't done it in a long time, but we used to quite a bit. While it is a risky thing to do there are also ways to make sure you're being as safe as you can about it. My husband isn't the type to not be able to pay attention to the road while something like that..now if it was me..that would just not be good, my eyes would be rolling up into my head and we'd crash. We also only did it on non crowded roads where the chance of having to break suddenly was less. Most times it was on back roads where we could pull off after a while and I could finish him while parked.
I voted no. It's not that I don't like it, I just think it's dangerous. We could kill ourselves and someone else. It isn't worth it. I'd rather pull over. Safety first!