I’m not so sure I agree... The new “multi-displacement” engines with the variable valve timing do an amazing job of economizing fuel use.
I have a ‘13 Ram 1500 with the HEMI - if I drive conservatively, I can get mixed-driving milage pushing 18mpg. Straight highway 22+. That’s right there with the F150 with an eccoboost engine and its turbo.
The Hemi’s have cylinder deactivation. I was driving a brand new 300C Rental Car and the “eco” light came on when it was running on four cylinders. As I recall, it got pretty good MPG and it hauled a$$.
The C7 Corvette I’m getting has the same feature and it’s Direct Injection as well. 460 HP and 30 MPG Highway.