I feel like I'm getting the worst gas mileage ever. I have to make the drive between Knoxville TN and Pittsburg PA alot and that means driving through the mountains of WV. I've got this display between the visors that supposedly tells me my current fuel economy, average speed, and miles left on the tank and it seems like its never even close. I've done all the regular tuning up I can from spark plugs to dif and tranny service. What can I do to get some better mileage out of my gas tank?

 

Coast down the hills?
Have you manually computed your average mileage? If so what is it, plus, what are you driving?

 

2001 TrailBlazer 104,000 miles now. Just did complete tune up 3,000 miles ago. I'm getting about 13 miles per gallon. The wonderful display always says average 17.5 I know all the mountains make it worse but I would expect that in a full size suburban, not the TrailBlazer.

 

There is a ton of "Do this for gas" threads. Do a search, you will have all the gas milage you could ever hope for. Those mountians are a bastard though.
Everyone knows the easiest thing to do to affect MPG is tire pressure, make sure you are aired up right. Then things like, staying off the gas, watching your tach, flushing your fuel system, making sure your thermostat is working correctly, a CAI, new exhaust, oversized tires are a no no, brush guards weight you down, roof rack withno deflector is bad, and about a million other things. Search it up.

One more thing, if you have the Auto4 option (the 4 button 4wd set up) make sure you are not using it unless necesessary as it will eat up more go juice.

13 MPG (while not being good) is only a little low from average 'round here. I drove mine from NC to OR getting about that. Sucked. But I am sitting pretty in the mid 14's now after screwing with only 3 pieces of the engine (MAF, EGR, Throttle Body). That got me roughly .6 MPGS, but I drive 75~80 mph, 80% Hwy, 50 miles daily, with my foot in it the whole time... Basically I drive like an *******. *shrug* That stuff teamed up with a Seafoaming and CAI is poised to take me into 15.5+ town. I'm Pumped

Don't underestimate the things that free up lost power. Using less "stomp the gas" to go up the hill and more "hey this thing has some *****" to continue up a hill will play into your favor as well.

Or buy a Carolla

 

I get like 18-19 mpg normally with a mix of city/highway driving so I wouldn't say 13mpg is a little below average.
Replace your fuel/air filter if you haven't, check your plugs for the proper gap/replace or regap if they still look good. If you haven't cleaned your MAF or EGR recently now would be a good time. Do the seafoam treatment before you replace your plugs, run a full can through the brake booster, 1/3 can mixed with your oil, and 2/3 of a can in your fuel tank.
You could replace your upstream oxygen sensors(before the cat. converter) as those will reduce your gas mileage. I would also check for vacuum leaks/exhaust leaks and fix as necessary.
Pretty cheap stuff most expensive would be the oxygen sensors but you should be able to do all of the above yourself and it could very well be worth your while.

 

i get around 12 average but thats with 31's before those i was getting around 14mpg. If you havent changed the fuel filter i would recommend than i gained about 1mpg

 

Swain, i was using This as my base line. AND I was looking at the wrong line Got me.
Looks like 17-18 is average so 13 is pretty low.

 

What kind of tires are you using, If you have any kind of off road tire you will get less mileage. I use Michelin X-Radials and I get about 20 - 21 MPG with my 89 S15 Jimmy. Use synthetic oil helps. K&N Air Filter will also help. Use cruise control whenever possible.

Synthetic Oil - Less Friction in the engine
Tires - Rolling Resistance (Less Resistance Better mileage)
K&N Air Filter - Increase Air Flow may help efficiency.
Cruise Control - Maintains a steady speed and therefore uses less gas.