Whats an US-Car? You may not mention but there are a lot of US manufactures on the german market. Did you mention Ford is a US company? They are so good integrated into the german market with smaller cars you may forgot Ford build maybe the most famous muscle car – Ford Mustang.
And thats what I call a US-Car. Of course it needs to be from the US, it needs a V6 or V8 (or higher) engine. And on the street you should hear and feel the engine. Thats what makes this cars famous. Its their presents on the street. You hear them from miles and their bulk makes them recognizable. Through their design they caches the eye. 10 years before there where much more US-Cars on german streets but now its a dying species.
The Pontiac Firebird was once the main model of Pontiac. Then, with a V6 engine it became the basic model – a so called Pony car. A “small”, “light” sportscar with a “small” engine. Fiero and Trans Am became the sport models with turbo V6 or V8 engines.”
So but back to the definition: At least 20 years old, V6 or V8 US produced sportscar – thats an US Car for me. Included are street cruisers which are not very sporty…but hey..we are family.