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.


Putting it in park at highway speeds depends mostly on how new the car is. Newer cars will put the transmission in neutral and probably yell at you with the dash. Older cars the parking lock isn’t strong enough to lock up the wheels at speed, so it’ll grind and clatter or just break. Ruining the parking lock.
Turning the car off on the highway just makes you coast to a stop. Depending on if its an automatic or manual transmission; you might loose power assist on the steering if the engine stops spinning. Pulling the key out normally activates the steering wheel lock. Which is a whole other problem if you are still moving… Some automatics prevent you from removing the key if the transmission isn’t in park though…
Makes sense. My car has an automatic transmission, I know that much. (Actually no, I have a CVT, and yes, I know it’s shit, but the car is paid off and it’s still going strong at 130k miles… dodged a bullet, it seems.) So I guess it would just sit in neutral until it’s stopped?
And yeah, makes sense about the key thing.
Ooh a CVT? Well that’s a different bag of worms I’m not directly familiar with, though I do know how they work and the nature of wear and tear of the parts they’re known for.
Honestly, I have no idea what would happen to a CVT if you put it in Park while driving, but I still bet nothing good…
You are probably thinking super old CVTs. Modern ones are great. Our Honda has 200k on it and CVT is fine. We did a fluid change around 100k and all was fine