I just keep a regular GI shovel in my car (it's a 4x4). My GF keeps a full size in her trunk, with the handle cut to size to just squeeze in. I've used it once, and was glad it was her shovel and not mine! Though, admittedly, I probably could have driven out if it was my car.

I hear the "grain shovels" are the best for snow. But I do fine with the flat-ish ones.