lbarnold3

I just drove about 4 hours with my cruse. Control set at 65. (2011 crew cab ) and got 20. 7 mpg. Very little stopping or slowing. If I go over 70 the mpg drops off to 16 or17 mpg.

basilkies

Wide or heavier tires and rims can lower your gas mileage, just jacking up the frame can cause more under carriage wind friction.

Putting higher octane gas than recommended is foolish. A change in octane changes the firing characteristics of you fuel meaning your spark plugs fire at the wrong time and your fuel ignites while the piston is still coming up. This eventually can creat pits in the piston heads that eventually wear the piston out prematurely. What I'm not sure about is if the modern computerized car can account for this octane problem. But anyway the first problem will be lower gas mileage because this is not an efficient way for the engine to operate.

Another gas mileage stealth problem is, getting back to tires and rims, wheel circumference changes. A bigger wheel will screw up you speedometer, you computer mileage readouts and gear ratios. It will be subtle probably not more than 10% change. You can check this by doing milepost check for 5 miles against your speedometer reading. You can also have the computer adjusted to handle a change. Of courses the dealer will milk you for five minutes of work, so if a buddy has a commputer programmer he can do it. I find it surprising that tire companies don't do this when they change wheels on vehicles.

jayvas

There has to be something wrong with my truck, no matter what I do, I can't get over 16 MPG.

dwbluvsaec

What gears do you have?

Dracoman

I have the same truck with a little less than 1,000 miles on it and I get about the same as you.

CGRB

I also have 2011 crew cab that get similar mpg. i have complained to dealer..no result.

i have 5000 miles, rarely carry loads, use no ethanol, drive on 4 lane highways most of time, have 5.3 with 3.42 - 6 speed, 4wd.

Best mileage on trip was 15.

basilkies

You guys are missing something here. Premium fuel has a different detonation point and requires different timing to make it work. So, just putting the fuel in without retimingthe engine will most likely reduce mileage. As for his mileage being bad in his Cleveland Buffalo trip, give me a break, 73 mph is bad news for mileage. If you want to see optimum mileage I would estimate it will be around 45 to 55 mph. Speed creates more wind resistance but to a certain point helps mileage, so you have to find the happy point where wind and speed are optimum for mileage. In a pickup windage is a bigger problem becauses the are so UN aireodynamic!

On the other hand I find the 8 cylinder/4cylinder feature in my pickup to be a joke, it rarely comes on and maybe could be a big help if you miles of downhill cruising included in your trip. Trouble is at some point you will have to go up the mountain and lose everything you gained. So, it may help on terrain that goes up and down a lot, but the results could only be measured against another truck that didn't have it because the situation where it works is a bad mileage situation already. So, it will only make a bad mileage run less bad!

abikerinpa

Don't feel bad , i just got a 2011 gmc sierra with a 5.3 4x4 6 spd auto and 3:42 gears and it gets like 13-14 mpg as well

abikerinpa

Hey guys and Girls , New to the forum and Just got a new 2011 gmc sierra w/t 4x4 with 5.3 with a 6 spd automatic with 3:42 gears , I was wanting to know if i could put in 4:10- 4:11 gears and run somewhat decent at 65mph ??? right now i can go about 80 @ 2100 rpms , But i was also was curious if i have do do anything else with computer or traction control etc when i go to change gears so it runs right with no computer errors popping up ? I would love to see it run about 1,900 to 2,000 rpms with the stock tires i have on it @55-65, all help greatly appreciated , thank you in advance ;-)

tsduke

Highway??