Self-destruct button
Whatever it takes to prevent a French fry from falling between the seats.
Penis-shaped gear shifters.
And the higher the gear you shift into then the longer and harder the gear shifter becomes.

Name a feature modern cars should have that doesn't exist?
That's a good idea the licensing would be really cheap for that.insane Clown Posse bumper stickers
Whatever it takes to prevent a French fry from falling between the seats.