It is TRUE, FACT, that the most popular, and therefore the most commonly owned American cars are big SUVs and trucks, and the average family car is bigger than the typical European family car (Focus/Golf sized).
These cars ARE bigger and ARE heavier.
They DO have softer suspension settings and more cushioning rides because that is what people want.
You pull out some figures representing a small total of either regions car outputs to "prove" your point.
Well, since you can get countless Caterham, Westfield, Radical type cars that weigh less than 500kg that must "prove" all European cars are lighter?
Of course there are cars in the USA that are light, and cars in Europe that are heavy, but how many people own a 2500+kg Rolls Royce or Bentley in comparison to a 1200kg Ford Focus.
How many people in America own a 950kg Mosler in comparison to a 2000kg F150?
You'd accept the phrase "Americans aren't astronauts" because a very, very small percentage of the population have actually been in space.
Why not "American cars are heavy" when the top three best selling cars in the USA are all 2000kg trucks, and very few are Moslers, Saleen S7s, Corvettes or even Mustangs.