Four Bikers of the Apocalpyse (or something like that)

[jamoche]

OTOH, if the Impala is a character (and it is) then info on what one of the Four Horsemen Pony-car drivers drive is also a spoiler :)

So War has a smoking hot red motorcycle - sorry, that's Good Omens.

So War has a smoking hot red vintage Mustang, then Pollution/Pestilence (as Terry and Neil put it, Pestilence just hasn't been the same since antibiotics took off) should drive a beat-up Pinto with a color that can't be detected between the bondo and primer.

We never saw Death's motorcycle, but given that Discworld's Death rides a perfectly ordinary horse named Binky, Death probably has a perfectly ordinary Volvo. (And if Death were played by Peter Wingfield, well....)

And Famine... something black, shiny, and as far from fuel-efficient as you can get.