Agree, the N-95 masks pack flat so they easily fit in kits that already exist — the FAK under my truck’s driver seat and the larger FAK in the main kit in back. Besides, for simple smoke at a distance such as what the folks in SF have now from the fires up north, a simple, cheap N95 mask is all you need. I’ve used an N95 in those conditions and a cheap N-95 mask is more than adequate.
For a fire that’s closer, where smoke is thick, and gasses may also be present and more than a nuisance, a mask that can handle gas/fumes as well as smoke particles is a better option. A real respirator is bigger & more bulky, but unless you have an SCBA, you need a filter system that can use the air around you; it needs to bring that air up to a quality that allows you to keep driving during your egress. The 3M half-face respirator KenK linked to above looks like a good option.