fredster

I've noticed something wierd with my gas mileage and would like opinions/verification. I live in Michigan and got my Tahoe on 9/25. For the first 1000 miles my MPG was lousy which I attributed to a tight motor. From 1000-3000 miles I was averaging 16-16.5 for my mixed commute and was getting 17.8-18 when running 73-75MPH on the expressway (long trip). Most of this driving was with temperatures in the 50-60 degree range. Last week the temperatures dropped into the 30's. My commute MPG suddenly dropped to 15-15.5 and the best I can get on the highway is 16.3. I also noticed that even running at 55-60 I could not get better than about 17.5.

Yesterday the temperatures crept up into the mid 50's. Guess what? My MPG's were back up, too. I was actually able to get 20 running at 60MPH and 18+ at 65. Then as the temps dropped during the evening (and during another trip) my MPG's were back down again.

So - does colder temps really affect my MPG that much? At first I thought it was winter-blend fuel here in MI but after seeing my MPG jump back up yesterday I am beginning to think the cold-weather calibration is less than ideal.

The Tahoe will go in at 5K for tire rotation, rear door trim replacement and an oil change. I'm going to ask them about the MPG's, but it would really be helpful if someone else can validate what I am experiencing.

BTW - I have tried 89 octane fuel - no change. I have tried different brands - no change. The Tahoe does seems to like fuel from Wesco pumps, but even that didn't make a difference when I tried it last week when the temps were cold.....

Dash

I replaced a 2004 Escalade that averaged 14 mpg, mixed driving. Although I really like my new LTZ, the first 600 miles have only averaged 12.5 MPG. I was convinced that it would be much better. Am I being naive to expect that the 8/4 config 5.3 should do better? I would like to know some mileage figures from those who have more miles on this engine. Thanks.

fredster

Dash - If you're doing pure city stop-and-go driving, 12-13 MPG is not unusual. Just running errands at lunch can pull my commute MPG of 16 down to 15 which tells me I'm getting a lot less MPG during all those starts and stops. If you read this and other forums on the Tahoe you will see that some people are getting 20+ and other people are getting 12. Is it really a problem or is it driving habits? I don't think we know yet with this relatively new vehicle.

I will say this. I'm a lot happier getting 16 in town and 18-20 on the highway then I am with 14-15 in town and 17 highway.

73shark

During the first 15-20 minutes of your commute you are dealing with loosening up all of the cold, stiff lubes and seals and that's a lot of drag. Ergo lower MPG.[:'(]

fredster

73Shark - I see your point, but over the weekend I made two highway trips of 150 miles, and my average would not get over 16.3. I actually covered over 550 miles over the weekend and kept a close eye on the avg mpg during the entire trip.

Friday night I filled up after 60 miles of highway driving, and was then driving secondary roads at 55-60 and could not get over 17MPG average. At that point everything was fully warmed up, but the temps were in the mid 30's. Two days later, I filled up after 40 miles of highway driving and was again driving 55-60 and was the computer was reporting an average of 19.5-20MPG. The only difference was that the air temperature was in the high 50's.

So......35 degrees and getting 17MPG......55 degrees and getting 20MPG.....both times fully warmed up and driving under very similar conditions with no changes in vehicle load, tire pressure, etc. No headwind or tailwind in either case....this is the mystery I'm trying to solve.....

If the issue was winter-blend fuel I would not expect to see my MPG jump back up to 20 just because of an increase in the air temperature.

If the issue were a cold vehicle vehicle (logical) I would not expect it to factor in when filling up with the vehicle fully warmed up and getting right back on the highway.

Thanks!

jasonw75

Fredster:

I'm from Michigan also, were you driving mostly north and south on one trip and mostly east and west on the other trip. The winds normally come out of the West/Northwest in my parts and I notice a significant change when driving with the wind vs. against the wind.

jasonw75

Your truck will continue to increase mpg until about 10-15K then it will steady out. Don't ever expect the 21-24 they say on the window sticker on the highway unless you plan on driving 55 all the time going down a hill with the wind at your back.

XM DUDE

The mileage test they do does not represent real world conditions either, so if you can get 18 MPG out of this 5000LB truck, that's pretty good.

golfer

It has nothing to do with the winter blend gas.

The colder it gets the more dense gasoline becomes ...the warmer it gets the less dense the gasoline becomes.

fredster

So if a 20 degree drop in temperature (55 to 35) dropped my MPG from 20 to 17 at 55MPH, what can I expect when it's 5 below? 11 MPG at 55? NOT.

Also if this were the case then maybe my Tahoe needs a heating element for the fuel tank much like my Duramax had an inline fuel heater?