[Lwerewolf]

Not too sure about the engines as of late. Bigger and heavier vehicles - yes, but still mostly rural/highway, and at way lower speeds than the EU. Overall, IMO it's just the distances involved.

[ponector]

Lot's of European cars have 3 cylinders instead of American V8.

[cpburns2009]

The majority of American ICE vehicles are 4-cylinder, not 8.

[etempleton]

There are almost no new vehicles in the US that still offer a V8. They exist, but make up a very small part of auto sales.