Explorer
Bronco Guru
A broad torque curve has everything to do with it. Lower rpms for a given speed is useless if there is not enough torque to sustain speed even on slight inclines. My son's Mustang is a stock 200ci I6 C4 and 2:80 gears. While it will get 24mpg, it is 1500lbs lighter and more aerodynamic. Add in free rolling street tires and I can't compete with that, even though I have roughly 60 more hp and a really broad torque curve. Really wanted to do a NV3550 swap, but can not make the overdrive useful till speeds higher than it will ever get driven. Even then, it is highly improbable I could reach more than 18mpg. It's a great little engine, but it is what it is. Won't even get into the expense aspect.