Always wanted to know this, always been afraid to Google it because I figured it would report me for self harm or something like that.
So, 1. What would happen if, while driving on the highway at highway speeds, you grab the gear shift knob and put it in park? Would it just lock up all the wheels or what?
And 2. What would happen if, also while driving on the highway, at highway speeds, you turn the car off (turn the key and remove it)?
I feel like both should be impossible while the car is in motion. But somehow I don’t think they are. And to a gearhead, these are probably really stupid questions. But as someone who barely understands how cars do what they do… I’m curious.


So you’d basically break your transmission. Sounds like something that shouldn’t be allowed to happen.
Once upon a time, vehicle manufacturers assumed people have common sense and know how to properly operate a motor vehicle. Then as time went on, they’ve discovered just how many idiots there are out there, so newer vehicles tend to have lockouts and safety mechanisms to prevent such things.
Still, its best to assume that no vehicle has any such safety features to prevent you from making either one of these mistakes.
Maybe. Maybe not.
I didn’t that time, but I immediately put it back in gear. Probably took a few years off the parking pawl.
Shifter systems are designed to prevent this - this car had a shifter issue we were working on.
It’s a hard thing to do any more, the lock outs have gotten a lot better. Pretty much impossible with push-button shifters.
Every car I have driven, with the oldest being a '77 manual, seemed to have something keeping the shifter from accidentally going into park for automatics or a gear too far down for a manual. I never tried to force it, but it seemed like they had functionality in llace to make it impossible or at least very difficult.
Note that you were replying to someone who said their car had a shifter problem