It’s been engineered that way. I have gotten as high as 56 mpg on my 2009 Cobalt xfe. 5 speed manual. Avg 60mph over 84 mile course. L.a. to Santa Barbara. Overall decrease in altitude about 1400 feet. Final drive ratio on Cobalt xfe was engineered for better mileage
Ever try push starting , or using the downward slope of a hill to start an automatic?
Not since they remo0ved the rear pumps from them 60+ years ago!
I've also, at 18YO, in a VW Beetle, had to start in 1st gear, because the clutch cable broke; then speed shift, until I could get it to the shop to replace the cable.
Drove it that way on the old 2-lane 101, from Crescent City to Eureka CA, cussing logging trucks, and timing stop lights as much as possible in towns.
“....using the downward slope of a hill to start an automatic?”
Some older GM auto trans cars had a hydraulic pump run off the output shaft. They could be push started.
Works best in reverse, pushing it backwards.