Cars? No. Might just be a bit of semantics, but you could not stretch too far beyond the horseless carriage appearance of super early, very limited vehicles.
I would not mind if there was another series added to the rotation of western (RD) and contemporary/80s nostalgia (GTA). But what I want from Red Dead is gunslinging and yeehawing. If they want a game set in the first half of the 1900s, that could be done as it’s own game.