Ive thought about this before an here are my thoughts (copies from my post on SimsVIP)
I really would like them back. My thoughts are, have them pull in and out of the drive (maybe have a short, long and circle drive item that allows this) and drive down to the "end of the neighborhood. My thoughts on this is people in the sims 3 were happy to have cars but pissed they just "appeared" on the road. so have driveway object instead of a parking space object would be a better option. this could have very specific rules to it so if the Simmer decided they wanted to place this object somewhere other than at the road it could just "appear" on the road when its time to drive off that makes it their choice.
Also i would want cars buy and sellable in the retail system along with a "broken down" model in the catalog that can be repaired. but would also want the option to "tune up" a perfectly running car.
As for community lots they could just have it appear in a parking space on the lot or have only the players car sit on the side of the road if there is no parking space/driveway available on the lot.
Gameplay activities could be car shows, buy/sell cars, woohoo/mess around/ makeout ofcourse, Drive in movie theaters for dates or parties, and a plethora of rabbithole things like car races insurance and even a possible career of mechanic sims bring cars to your shop and you walk around fixing them maybe a "similar" diagnosis system to the doctor. New trait could be something about car enthusiast or born mechanic
