We used to have a lot of 4 cylinder motors in American cars. Heck, I remember in the 80's, the base motor for the Gen3 Camaro/Firebird was a 4 banger,
2.5L with like 90hp. Ford Mustangs(2nd/3rd Gen) used to have a 2.3L 4 cylinder and the Pinto started out with a tiny little 1.6L. Most of this was back in the 70s and 80s, however. Even straight 6's are rare these days, except maybe some base model pickups and SUVs. Jeep was huge on the I6 for the Wranglers, but I think they finally quit making them (not a big Jeep follower). Aren't some of the heavy duty truck diesel engines based on an I6 configuration?[/quote]
Every time I read something like that, I'll ask myself how the american domestic engines could extract so small amount of power from such a huge I4 displacement... 2.5l for 90bhp

. Here (Italy) in the '80 we had a FIAT 1.5l with 85hp. The 1.6 had 100 (and they weren't futuristic technological masterpiece).
I really want to understand the differences. (emission regulations?)