Used to get this from significant other, but the new cars with the large centre consoles ( at least in the cars we buy) are too big/wide/uncomfortable to permit this happen anymore.
Also, when you cum, if you are concentrating on that, you will be very distracted, if you are concentrating on driving, is it really worth the effort.
Old pickups with bench seats were great for this activity. Plus was way less traffic back in the day.