SO at 70/75 in 6th being close to 1700, is that too low of a highway engine rpm , or should i drop it ff to 65 in 5th gear? just some food for thought

the old school way to find the engine's sweet spot is to watch a vacuum gauge. The higher the vacuum the better the mpg. But that ignores the forces of aerodynamics. Few cars can continue to gain mpg over ~70-75 mph.

my trailblazer gets its best at flat road 80-85 I have 3.42's and 33's, so the final drive ratio is really low... it actually does very poorly at 70, but i've gotten 17 mpg with 2 ppl gear and bad aerodynamics on a trip from va. But the t/a seems to enjoy 75, fast then that and the suspension sucks (i think the previous owner beat on that part of it too much...:lol:

cars been recalibrated for the different tire size and gear ratio. Yup windows were closed the whole time, i understand how aerodynamics works. Also being that the cars lowered that's less dirty air going under the car.

just for food for thought ill start drivng closer to 2,000-2,200 rpms and let you guys know what my gas mpg is.

All i can say is im the one laughing to the bank on the money im saving on fuel.

That's what I do. GTP gets pretty decent milage that way.

Mark42 is that you?