Totally depends on the car. I know of cars where it has to be done in the workshop with the diagnostic computer. Other cars like my current car it is a menu item on the touch screen display.
Every car is different read your owners manual.
On a 2014 Chevy Impala (I picked a GM vehicle pretty much randomly), this feature can be adjusted according to the Owner’s Manual (PDF).
Apparently, if you drill down through the menu in the audio system (starting on page 5-40), you will eventually get to “Auto Door Unlock” (page 5-43). This sets which doors will automatically unlock when the vehicle is shifted into Park. Your choices are:[ul]
[li]Off[/li][li]All Doors[/li][li]Driver Door[/li][/ul]
It looks like you can set all kinds of stuff in there. Many people, I’m sure, never realize this and for their entire ownership of the vehicle live with (possibly while bitterly complaining about) the defaults.
Vehicles with less sophisticated audio/navigation systems may have far more arcane methods of achieving the same thing, as ethelbert pointed out. Our 2009 Honda Odyssey has automatic locking and unlocking defaults that can be changed, but doing so requires a very non-intuitive sequence of actions involving button presses on the remote, hitting the lock switch, and maybe sacrificing a chicken. It’s in the manual somewhere…
Was I the only one who first read this as “So there are several lawyers involved.” ???
my 2012 Honda Civic locks the doors when I reach a certain speed (maybe 10 mph?) I reset it according to the owner’s manual instructions to unlock all doors upon shifting into park. This suits me just fine.
I wonder if the OP’s borrowed car has a fob with door lock/unlock buttons? Wouldn’t it be easier to just use those when getting something out of the back seat or trunk, then lock it all up and be on your way? Or are you getting stuff out from all over the vehicle and then getting back in to drive? Put things within arms reach instead? I’m just trying to think of what I ever needed to get in and out of the car to get while driving and I’m coming up with nothing.
I like the auto-lock, personally. I drive in the city, and have most certainly had people just walk up and try the door when I’m stopped at a light. Since I’ve been a vigilant door-locker for a long time, I’m happy to have the procedure taken out of my hands and I don’t have to worry about it. I find the 4-door snick as I put the car in drive and press the gas reassuring.