It is a copy of it. It is a 1964 Vollstedt, which was one of the first American built mid-engine Indy cars alongside the Thompson-Buick powered cars, also copies of the Cooper.
This is a Lancer body.
"In 1963, Vollstedt constructed an Offenhauser-powered, rear-engine Indy car, which Sutton proceeded to qualify in eighth place for the 1964 Indianapolis 500."
He blew the engine on lap 140.
The car was so good that A.J. Watson made two copies of it, one Offy powered, one Ford four-cam powered. This one should have won easily, running on methanol instead of the Ford recommended gasoline, but had to stop too many times due to a malfunctioning valve meaning that only one of the two fuel tanks provided the fuel. It still finished in second place to Foyt's antiquated front-engine "roadster."