Mileage Question
 

I have two H3s. One I bought new in 2006 and a 2008 I bought a couple of months ago. Both are 5-cylinder models. The 06 (the one my wife stole from me) has about 124,000 on the clock gets about 16 MPG around town and about 19 MPG on the highway. The 08 I just bought (the complete cylinder head just being replaced by a GM dealer) with around 85,000 on the clock gets around 13 MPG around town and maybe 15 on the highway. The 06 is an adventure package and the 08 is a base model. I am just wondering what would make the mileage figures so different between these two vehicles. The only exterior difference is the 08' car has OEM roof racks. I can't imagine that would make any difference around town. The 08 has a new cylinder head and a lot less mileage on it and the MPG is about 3 MPG less that the 06. :confused:
Ideas, comments, suggestions, let em' rip................

measure miles with gps??
tire size,calibration?

I measured the miles using the odometer. I have the standard size tires inflated to 40 PSI.

Your wife drives a lot different than you do. The 06 has a 3.5L and the 08 has a 3.7L.

You would need to measure mpg between the vehicles with the same person driving. Even if you swap trucks for a week, your comparison will still be affected by weather, driving routes, and traffic, etc...

My wife does drive differently than I do. She has a heavier foot on the gas pedal. I wouldn't think that the difference in engine displacement would make all that much of a difference, especially since I am more of a gentle driver and the 06 with 123-thousand (all original) miles and the 08 with 85K just had a brand new head installed by a local GMC dealer. Plus, my wife's 06 has 285 tires and mine has 265s. I upped my tire pressures to 50 PSI. We will see if that makes a significant difference. It seems to roll easier and the ride is OK. Her tires are Yokohama Geolanders and mine came with Ling Long Crosswind tires. I know mine are Chinese but they are brand new and I can't afford to change them to buy a better quality tire. I'll have to wear those sucker out first. The Yokohama tires have performed well. Time will tell with the Ling Longs. As soon as I can test the mileage with the upped air pressure, I'll post the results.

The difference in mileage does seem like alot, but there could be a number of factors in addition to driving habits & weather/conditions. Different brand/size tires can indeed affect mileage; the weight of the tire alone can be a big drag on the engine. Her taller tires may in fact be lighter than your LingLongs, meaning that they are easier to get turning AND result in a slightly lower RPM once moving. Rolling resistance can also be different, affecting mileage.

Well 650Hawk, you are spot on the money. I aired up the Ling Longs to 50 psi and took it out for a test drive. The ride was not harsh and the H3 seemed to be rolling easier. This morning I gassed up and drove a 40 mile round trip on Tennessee country rolling hills highways with speeds ranging from 30 to 55 miles per hour. I fueled up and checked my mileage and I got 20.5 MPG. That is a BIG difference from the 15 MPG I was getting. I am actually amazed at the difference. And, the ride was smooth and not harsh in the least.
I guess the tire pressure should be comparable to the weight of the vehicle, etc. I will be staying at 50 PSI because all seems to be happy there. Who wudda thunk it?:D

Driving over-inflated rice rubber and in bliss. :rolleyes:

Like Bugs Bunny used to say: "what you don't know can't hurt you". Until it does.

I am only running 5 PSI over the max on the tire. I am not too concerned about a tire exploding. It's not like I am driving 75 MPH through Death Valley in 120-degree heat. Besides, the sooner I run these rice runners bald, the sooner I can buy a set of first rate tires. But, so far, no complaints on the Ling Longs (except the name on my tires:(

Wonder why they put MAX PSI on a tire?:rolleyes: