Let me get this straight, lower gear ratio = higher engine rpm @ a given speed = better mpg?

Somehow, this doesnt seem to add up.

 

yeah but auto trans = shifting at a certain rpm no matter what which = lower rpm which = better gas mileage.

 

Keep your tires properly inflated. A fuel filter may help. Like others have said, MAINTANCE!!! Depending on how many miles you have, you may need a full tune up,and dont be a lead foot.

 

You want to keep the engine in the torque band. When I had 3.55's and my 33's I was turning 1600-1800 rpm on the freeway. Any time I had to speed up even just a little bit I had to downshift the trans in order to actually move. The truck I noticed liked to be at 2000rpm and up, where the 4.6 starts making good torque but in order to do that I was going in excess of 80mph and I don't need any more speeding tickets lol. So after putting in 4.30's 65-70mph is between 2300-2500 rpm in overdrive and I am just resting my foot on the gas pedal to stay at that speed. Engine is not working as hard but still is not turning too fast which in turn gets you better MPG. Now if I drop into 3rd your looking at 3500rpm at least and that would kill your mileage if you had a 3 speed trans.

 

I still need to calibrate my speedo it says im doing um er about 85mph when my GPS is telling me im actually doing 73 lol

 

my truck is like the complete opposite. when im doing 70 with my stock 31.5's, im at about 2100rpm. when i do 60 its about 1600rpm. 70 gets me 10 mpg, 60 seems to get me about 15-16 im not exactly sure, but its definately better than 10.

 

thats weird because i have a 02 SC Fx4 5.4L and average about 15-16. usually 15. and hawaii isnt flat.

 

haha that must suck i get 15 City and 16-17 Hwy and im not soo aerodynamic with 10 inchs of lift. engine wise i only have true duals, gotts mod, tbs, & edge Revo. but yea like everyone said its all in how you drive.

 

I get about 13 and i have 165k on my 4.6 it has no mods on it except a k&n air filter, I dont drive far to work and school is a 15 mile round trip that i do 4 days a week. Im ok with 13

 

why is mine 05 5.4 getting like 12 mpg? my grand dads did the same thing. and i drive it easy... and do the speed limit