Open-wheel cars differ from sports/racers in being "pure" race cars built to a certain set of rules & restrictions, or "Formula".  Still, considerable variation is possible within a given "Formula", especially in the earlier cars.
 

Larry Menser of nearby Carmel in his 1960 Meskowski Indy car.	Philippe de Lespinay drove his Cooper, the car that Jack Brabham drove at Indy in 1961.
Dave Olson in the proto-Formula 5000 Holynski-Chevy.	Don Orosco always runs interesting cars.  This is a 1958 Lotus Mk.16 Formula 1 car.