Comics Alliance regularly features covers for comic books that never existed, but should have. They are written by Chris Sims and drawn by Rusty Shackles. The latest is Superman vs. Flash vs. The Dukes of Hazzard.
"DC Super Stars #27 (March-April 1981): When Boss Hogg sets up a phony charity designed to funnel contributions from well-meaning citizens into his own pockets, Superman and the Flash are roped into holding a charity race across Hazzard County--without super-powers! But when Bo and Luke Duke, a couple of good ol' boys who never mean no harm crash the race, can the two Fastest Men Alive outrun a souped-up Dodge Charger before it hits the county line? Find out in this exciting issue! Also featured: Lois Lane discovers a Hazzard County fashion statement sure to catch Clark Kent's eye and a two-page backup story where Jimmy Olsen and Kid Flash meet Coy and Vance!"
There's a complete archive here.
What's your idea for a great pair-up that is unlikely to be ever seen in an actual comic book?