Sal Trapani's inks on Mod Wheels for Gold Key make all the stories involved look pretty much alike—at first glance. Jack Sparling's pencils on the first issue are pretty hard to hide, though. After that, Jack Abel's angular faces show through, even without the later ruler-straight inking he gives his own pencils when Trapani leaves.
Amid the Abel stories, issue 5's first story ("The Midas Run," February 1972) is pencilled by an artist who at that point was working solely for Charlton—officially. Charles Nicholas had worked for a number of companies before settling down at Charlton in the mid-Fifties. He'd end up at DC in the later Seventies and early Eighties.
The Gold Key editors who, as Len Wein told Mark Evanier, didn't realize they were getting Jack Abel's work when they hired Sal Trapani, doubtless had no idea they were getting work from Nicholas as well.
Charles Nicholas' art is so undistinctive as to be distinctive. His stock poses are geometrically set within the panels. In the same issue's second story, Abel has a couple of faces set solidly in the foreground, at panel's edge and facing directly across the reader's line of sight; that's one that Nicholas uses all the time, as in the sixth panel here. But Abel doesn't use Nicholas' trademark pose, seen here in the second panel. The character faces directly toward the reader as if set there with surveying equipment. Abel's poses are more dynamic. (And he's much better at car-and-road perspective, a useful skill on a comic book about automobiles.) This story would be even more typically the work of Nicholas only if in panel 5 Wheels faced front as solidly as Houston does in panel 2; the faces at a precise ninety-degree angle would be a quintessential Charles Nicholas layout.
Abel and Nicholas aren't the only ghosts Sal Trapani used at Gold Key. More to come...