americans have historically been very bad at getting any kind of fuel mileage out of them...you could technically make a 2-3 Liter V8,

Remember this little 3.5?

The Rover V8 began life as the Buick 215, an all-aluminium OHV pushrod engine introduced in 1960 for the 1961 US model year (it was on their drawing boards in the late 1950s).