Mufflers would be illegal. If you are driving between states, you need to check to see if your driver's license is accepted by each state you go through -- and some counties. Adjustable car seats are illegal. Automatic transmissions are illegal. Building your own car would be illegal. If your truck is too short, it's a felony. Unless you call your truck a car, and never put anything in the bed. If you have a criminal record for drug use, you cannot drive a car, or even ride a bus. Some states will only let you put 5 gallons of gas in your tank, claiming that large gas tanks are a risk for ramming attacks. California will only let you purchase cars they say are safe--and haven't updated the roster for years. Politicians keep insisting that your tires should be laser etched with microscopic serial numbers so you can track down criminals by the tire marks left behind, and that your car should have a kill switch controlled by the government. Movies like Fast and the Furious get blamed for causing drunk driving. If you buy a Tesla, people constantly demand that you explain why you NEED to own it, and that everyone should be perfectly fine with a Vespa scooter. Whenever a drunk driver hits someone, society blames you personally, and says that you just want your dumb hobbies and don't care about children.