My old 4x4 has a Taurus 650 hidden below a dash panel that looks like it is screwed down but isn't. My old Bug has a fairly thick steel strap that can be unbolted from under the dash so any OWB, beltslide, or pancake holster can be mounted within reach but completely hidden under the dash. Right now it has a Walther P-1, but used to have a 2 1/2" S&W Model 66.
I think that stainless is a better choice if you don't plan on ever looking at it to see if it is rusted or clean or whatever.
HIDE THE DAMN THING!
BIIIIGGG SHOCKING STORY: "Someone broke into my my house and somehow they new I hid my money in the top sock drawer of my dresser, and I'll be danged if I can figure out how they found my 2 guns. One was under the bed, and the other was in the corner of the closet right behind my t-shirt." Crooks aren't all stipid. If I turned crook and broke into a car looking for a gun, I'd look under and around the seats, in the door pockets, the pockets behind the backs of the seats, in the glove box, and in the console. I bet 95% of people that have a gun in their car or truck have it in one of those spots.
HIDE IT WELL, & IT WON'T GET SOLEN! Put it within reach under the dash or somewhere else. I've had a couple of cars I thought about removing the passenger airbag and mounting a holster of some kind in its place behind the hinged panel.
If you are really worried about it being there and getting stolen, here is something to think about. A coworker just had all but his favorite hunting rifle and his .22 stolen out of his house. The other 2 guns were in his old 4x4 truck which wasn't locked and was in the driveway right in front of his house.
My long-winded $.02, hide it really well or lock it up in a strong steel box.