Chagne In Mpg

mattd · May 9, 2008

i have an 00 gmc 1500 4wd. i got it used with 67k miles. b4 we moved last summer i was getting 17.5mpg, with the best tank at 18.25. that was doing about 90% highway, and a 26m trip to work. now i drive 75% hwy, and 13m trip, and was getting 14.5 with the same driving habits. i dropped down, from 62mph to 55mph on my way to work, changed plugs and wires, added a cold air intake and took tire psi to 41psi, and am now getting just over 16mpg. still not too close to my original mpg. so my question is....does the small change in hwy driving and the diff in distance make that much diff? or should i be looking for another issue?

ak63 · May 9, 2008

A couple of thoughts. I notice my summer mileage is almost 1 mpg better than my winter mileage, and about 0.5 mpg better than spring/fall. When you moved did you switch from 100% gasoline to an E10 area? Some states allow E10 to be sold without labeling, or even mandate all gas sold is E10. This degrade fuel economy. What are the gradients like between your previous commute and current? Finally I've read elsewhere in the forum that you should check your MAF sesnsor (clean and/or replace) when you notice a fuel mileage reduction.

hubbycap · May 9, 2008

A couple of thoughts. I notice my summer mileage is almost 1 mpg better than my winter mileage, and about 0.5 mpg better than spring/fall. When you moved did you switch from 100% gasoline to an E10 area? Some states allow E10 to be sold without labeling, or even mandate all gas sold is E10. This degrade fuel economy. What are the gradients like between your previous commute and current? Finally I've read elsewhere in the forum that you should check your MAF sesnsor (clean and/or replace) when you notice a fuel mileage reduction.

The computer will lean the fuel in response to warmer, less dense air to maintain the correct air/fuel ratio. Just as aircraft do at higher altitudes.

99silverado1500 · May 9, 2008

I am just wondering how people get higher then EPA ratings in MPG.....I must be doing something wrong with my truck.

May 9, 2008

Lead foot

99silverado1500 · May 9, 2008

I used to have a lead foot and got 11.5 mpg, and i had liposuction in my foot big time when these fuel prices kept climbing, and i am up to maybe 12.7.

scottmoyer · May 10, 2008

Central Florida started pushing towards E10 in MArch and the mileage decline is substantial. My 06 was getting about 16.8mpg on my daily commute. I'm down to 14.8-15.2 on that same commute now with the E10 fuel. On a 22 gallon fillup, that shows a 44 mile drop in distance traveled. I am now buying 3 gallons of gas as $3.59 that I don't get to use because of this!! The prices have not changed with the change in fuel type here. Nothing like throwing $10.50 away at each fillup.

hubbycap · May 10, 2008

Central Florida started pushing towards E10 in MArch and the mileage decline is substantial. My 06 was getting about 16.8mpg on my daily commute. I'm down to 14.8-15.2 on that same commute now with the E10 fuel. On a 22 gallon fillup, that shows a 44 mile drop in distance traveled. I am now buying 3 gallons of gas as $3.59 that I don't get to use because of this!! The prices have not changed with the change in fuel type here. Nothing like throwing $10.50 away at each fillup.

The use of E10 reminds me of the smog pump of the 70s. Whereas the volume of exhaust was increased by pumping air into the exhaust manifold so that the combustion pollutants measured as a smaller percentage of the total exhaust. Thereby passing pollutant reduction requirements measured in parts per million of the total exhaust. I bet the engineers giggled their MFAO on that one. The pollutants were actually more since it took parasitic power to compress the air. What a boondoggle.

What the hey does 10% ethanol accomplish? More profit for Arthur-Daniels-Midland?

yukondan · May 10, 2008

Central Florida started pushing towards E10 in MArch and the mileage decline is substantial. My 06 was getting about 16.8mpg on my daily commute. I'm down to 14.8-15.2 on that same commute now with the E10 fuel. On a 22 gallon fillup, that shows a 44 mile drop in distance traveled. I am now buying 3 gallons of gas as $3.59 that I don't get to use because of this!! The prices have not changed with the change in fuel type here. Nothing like throwing $10.50 away at each fillup.

Same here in South Florida, E10 added to fuel and I noticed a drop in MPG. I have not found any stations local that do not now have E10.

It's like a double wammy, raise the cost of gas and add E10 to make you use more..........

Ranger · May 10, 2008

Yeah no kidding, here in Orlando I'm seeing more stations with that "10% Ethanol" sticker...Used to be just the one station by the airport, now it's everywhere, even the one station I thought I'd be "safe" at by my house. Thought it was just a coincidence, but I had started being forced to use E10 right around the time I got my tires so I marked it up to the bigger tire thing....Right now I'm at about 13.5 mpg on this tank.

rogerf · May 11, 2008

Central Florida started pushing towards E10 in MArch and the mileage decline is substantial. My 06 was getting about 16.8mpg on my daily commute. I'm down to 14.8-15.2 on that same commute now with the E10 fuel. On a 22 gallon fillup, that shows a 44 mile drop in distance traveled.

Welcome to the club...the safe, per tank mileage in my Impala went from mid-400's to lucky to get past 380 when this swill hit the market in Ohio a year & half ago. First though it was just the winter blends but it didn't improve when summer came around. Something is just wrong in this math...10% alcohol = 20% reduction in mileage. I swear this is why the EPA re-rated the fuel mileage estimates on every vehicle last year.

hubbycap · May 11, 2008

Central Florida started pushing towards E10 in MArch and the mileage decline is substantial. My 06 was getting about 16.8mpg on my daily commute. I'm down to 14.8-15.2 on that same commute now with the E10 fuel. On a 22 gallon fillup, that shows a 44 mile drop in distance traveled.

Welcome to the club...the safe, per tank mileage in my Impala went from mid-400's to lucky to get past 380 when this swill hit the market in Ohio a year & half ago. First though it was just the winter blends but it didn't improve when summer came around. Something is just wrong in this math...10% alcohol = 20% reduction in mileage.

I wonder what effect 10% water would have on gas mileage.

mattd · May 11, 2008

i guess it was the shorter commute that was changing mpg. i drive my truck to work, and if i go anywhere else with it i'm towing my boat, so never get an idea of what my hwy milage would be outside of going to work. but this weekend i drove 430m round trip w/out towing and got 18.47 mpg. so, not only is the diff in commute the problem, but i also just got my best tank, mpg wise, thanks to the mods i have done, as well as keeping my mph down. i still plan on doing a dual exhaust and getting a tune, so maybe i can even get it up to 20mpg.

another thing i tested. on the way there i followed a semi for about 50% of the way, and averaged about 75mph, with constant changes in speed, because of hills. on the way home i just did 65mph using cruise. and i got the same mileage.