A unopened one shot loaded with HP5 is or slower B&W, would be the only camera I might leave in the car, and in a cooler at that, for any long period, just to have it in case of an misadventure, as film is still preferred, in my mind at least, over digital for legal reasons.
Otherwise, I always have some kind of daily carry camera with me,eve if it's just a XA II or Minolta 16, but usually a F1N AE or Spotmatic or an FG, which is on line to be used with the Nikon F in need of a new finder.
As for Yashica 35s, I consider these colour cameras, as they are just too good in rendering colour to be loaded with B&W.
I do have a Minolta 9 that I could use as a carry camera, but some how do no, nor other cameras that are good ones, but always used with another camera or format.
In Medium, if it's no my Hasselblad 500 cm, the Minolta Autocord, (1958 'E') or Primo Jr., but the Primo needs a new skin and the other possibility, including the Super Ikonta 6x6cm needs a CLA still.
Diana, and other small point and shoots, and small rangefinders are usually carried in the company of other 'Real' cameras, but none of these would be left in the car, for longer than a hour or two, still in a bag or the cooler.
Leaving a camera, in the car is to be 'ready' for opportunities or need, yet courting possible damage to the operation of, or the film in, makes little sense, when carrying is as easy as a everyday carry of wallets or a couple of knives, SWK and Fast Knife, some bit of Cord or String, a couple of large and small Safety Pins, or your daily carry firearm.
You just pick it up on your way out and it's there for you, always.
IMO.