I'm just asking because I don't know. My friend asked me if he can go test drive a car at a dealership and video record the test drive. Can he do it without asking the dealership? Yeah, I honestly don't know how to answer him on this one; I don't know the legalities.
Why? Is that to help recall details of things like ride quality, acceleration, handling, etc?
There's 2 parts: recording the drive and recording the sales person in the car with him. The legalities of recording another person without permission varies by jurisdiction. Recording the drive itself is probably OK, provided it's hands-free. (Under no circumstances should the recording be allowed to interfere with safe operation of the vehicle.) And be aware that if something goes wrong, the evidence could be used against him.
Unless there is a compelling reason, though, I wouldn't. If he wants to remember details, just take notes (written or voice recorder) as soon as the drive is over. If it is for entertainment purposes (a YouTube channel or something) ... absolutely not - get permission.
By the way, you'll probably get a better answer from a site that specializes in new car sales & reviews, like AutoTrader or "Your auto advocate" (joinyaa.com). They'll know more about those things than a maintenance & repair site like this.
