Even on cars that support it, it has always told you that you need to close Steam to put the car in drive. They don’t let you play any games while the car is in motion.
It’s been a decently good feature to have; the few times charging was a bit slow for me, it was nice to be able to play FFVI or Secret of Mana to pass the time. And it even synced my saves for when I got back home.
Ooh, you beat mine: 848330 (unfortunately, mine was hacked over 5 years ago, and by the time I realized, their logs didn’t go back far enough for me to validate that I was the original owner)