$1:
Engine start button
These are becoming increasingly common on many new cars, but aside from making you feel a bit like Batman, they serve no additional purpose at all. Once again, there's nothing wrong with the conventional ignition key set-up and, more to the point, you'll need some sort of key to unlock the car anyway, and so what do you do with it when you're inside?
The keyless entry number pad?? Won't need any keys then.
Now,if you wanna talk useless, we had a '64 Plymouth Belvedere with a push button transmission.
As for the push button starter, that ain't exactly new to cars.