I don't know if the Crown Vic or Grand Marquis versions sold to rental fleets now still have bench seats. The middle seat may not be large enough for adults, especially for a long ride.

There's also no way to guarantee a premium car won't be a Buick Regal or other such smaller car. But if you can manage to get one of these old boats, it might be cheaper than the Hertz minivan from BUF.

(FYI- Downtown Buffalo has cheaper one-way regular cars, but their one-way rates for large vehicles are higher.)