The Harley is definitely an icon of pure Americana - not so sure about the Cobra though. 'Vettes, Mustangs, Camaros, Chevelles and GTO's maybe. They were built and sold on both sides of the pond and other than the drivetrain, everything else about a Cobra - a small, low, 2 seat superleggera design, is *ahem* pure European!
If a modern day Shelby-like character took , say, a Honda S2000 or even a Miata and crammed a V8 into it, beefed up the suspension and chassis and flared the fenders for some fatter rubber; then took it out and kicked arse on the racetrack - would you endorse the modified "ricer" as pure Americana?