Are you looking to replace the cushions, or cover them? "Seat covers" takes me back to the '50's and '60's, and terry cloth seat covers to keep from burning our ass on hot seats. At one point, until some of the older siblings went off to college, there were as many as 9 of us crammed into old sedans, with no AC. The younger ones were sitting on someone's lap, so that was our seat cover.
My dad worked a day job, and ran a poker game 5 nights a week for almost 40 years, and all of our vehicles came from a couple of used car dealers who sometimes owed him money. By the time he picked up a red '60 Coupe deVille, and a silver '64 Sedan deVille, both with AC, the only one left at home was my younger sister.