So, we all know how certain cars flip if you go too fast (peel p50), so I have come to suggest front stablizers. (Basically training wheels for the front of the car.)
With it, I also suggest custom license plates, hydraulics, roll cages (different levels of strength), hood ornaments, and options for Rocket Booster placement (like 2 smaller boosters on the side instead of one big one in the back).
There are more ideas I have (mostly customization), but I don’t want to dump all my ideas into one post. (I also have ideas for vehicles, but that’s a different can of worms.)