Last post on Jul 01, 2011 at 3:11 AM
You are in the Chevrolet Malibu Maxx
What is this discussion about?
Chevrolet Malibu Maxx, Fuel Efficiency (MPG), Hatchback
#2 of 40 Sudden loss of mileage!
May 16, 2006 (5:23 am)
Got an 05 MAXX that I enjoy. I was getting a rock steady 27 MPG average driving in the D.C. area daily. I've accumulated 14,000 miles so far. Mileage has been a plus... up till now.
A month ago, I lost my dashboard power, HVAC controls, and radio. It wasn't a fuse, but a bad 3controller unit. The controller had to get replaced... under warranty.
At the same time, gas prices surged from $2.65/gal to $3.05/gal and I also understand that we are swtiching over to E-10 fuel (10% Ethanol).
Well, since I got my car out of the shop, my MPG has dropped greatly from 27 MPG to 22 MPG.
What happened? The repair, E-10 switchover, or both?
#3 of 40 Re: Sudden loss of mileage! [bimmerboy750]
May 16, 2006 (2:30 pm)
You dropped almost 20%. There was a study released last year, maybe biased , from the American Coalition for Ethanol that averaged only a 1.5% drop in MPG with E-10. You can find it with simple Google search
Are your MPG numbers based on your own calculations or from DIC??
If the module replaced in vehicle was one that does the MPG calculation then it is possible that you are just seeing the effect of some initial lower MPG driving and after a while your average might get back to where it was.
There is another potential - in the past folks have posted that the DIC display for MPG was a bit optimistic. There might be a potential that the calibration was updated (but that wouldn't explain that big of a jump).
#4 of 40 Re: Sudden loss of mileage! [e2helper]
May 17, 2006 (6:27 am)
I read those figures from the E-10 site earlier. I;ve also read about observed MPG reductions as high as 25%! What am I gonna believe? Probably my wallet.
The MPGs quoted are from from DIC. I reset the MPG about every 60 days. It always converged on 27 MPG. I suspected module replacement and shop time (running engine at idle for extended times, short test drives) would have had an impact too. MPG from the DIC coming out of the shop was around 10 MPG. I drove it without resetting it for about a month and it converged on 22.3 MPG. I reset it yesterday. Looks like it's converging on 22 again. I have some 5 mile stretches of highway driving and it appears that the MPG is not getting above 27 MPG on those intervals!
I drive 75 miles a day, 5 days a week (375/wk) (I don't keep track of the trip odo).
What I need to do now is go through my gas receipts over several months (I keep 3 months of receipts) and see if I can recount the gallons consumed in the 2 months before repair and the one month afterward. I should've been putting in about 14 gal / wk. giving me about 26.8 MPG measured at the pump before the repair. Now I may be filling up no more than every 6 days or 16+ gal/wk.
I'll report back on findings. If this is happening due to E-10, then people need to know.
#5 of 40 Re: Sudden loss of mileage! [bimmerboy750]
May 22, 2006 (5:49 am)
I am still tracking this issue, but I think I found a smoking gun.
MY other vehicle gets 24+ MPG highway. That has been rock steady for years up until recently. This weekend, I reset its MPG display for a long highway trip. My best average has also fallen to 20 MPG!
Two vehicles (one GM one Dodge) both experience about a 20% loss in fuel economy. What's going on here?
I'm curious to hear from other Maryland drivers.
#6 of 40 Re: Sudden loss of mileage! [bimmerboy750]
May 23, 2006 (10:44 am)
I burn E-10 here in northern va....and do about the same drive.....Im getting about 375-400 miles per tank in the highway/city driving.......I do 75 mile round trip a day...mostly toll road, 495, to Alexandria....I dont notice an appreciable difference in my Maxx....67K on mine....all OEM and no warranty work or updates....
just filled up on Monday with just over 300 miles on the trip odometer....DIC showed 27.4 MPG and average spd of 43 MPH, I reset it at every fill up....experienced shows me the DIC is 1.5-2.0 MPG off in the calculation.... and still had a 1/4 tank at fill up....
#7 of 40 Re: Sudden loss of mileage! [pao]
May 26, 2006 (12:14 pm)
My average now (shown on DIC) is up to 24.3. That's an improvement (without doing anything different). but still off from the 26.7, now about a 10% difference. If could find some whole 87 octane (no ethanol or MTBE), I could do a fill-up and drive comparison.
#8 of 40 Mileage with E-10
Jun 22, 2006 (12:23 am)
A gallon of ethanol has about 2/3 the energy content of a gallon of gasoline. So, if you are getting E-10 (10 percent ethanol), you are buying about 96.5 percent of the energy that you'd get with a gallon of straight gasoline.
Given that, if you are getting 29 mpg on ethanol, you'd probably get about 30 mpg on straight gasoline.
I have an '05 Maxx and try to run it on straight gasoline unless I'm somewhere that it's not available. I do notice a drop in MPG on ethanol-blended gas, but the specific amount is hard to say because so many different factors affect mileage. Overall I average a little over 30 mpg in my Maxx, and that's about 80 percent highway and 20 percent city. I try to drive at a reasonable speed on the highway. Fast interstate driving (75-80 mph) pulls the mileage down to about 28 mpg.
Has anyone ever noticed how the DIC always displays certain mileage figures, like 28.7, 29.4, 30.2, 31.8, 32.7, etc.? (Except for right after you reset it, when numbers can be different from those.) I think it does that because it actually calculates mileage in metric terms (liters per 100 km), rounded to the even decimal place and then converts it back to the English system.
#9 of 40 '07 mileage figures, anyone?
Sep 19, 2006 (10:54 am)
Anybody out there have some feedback on the '07's for mileage?
The MPG this year was rated lower, but that may be due to changes in how MPG's now being calculated.
As for my '04 maxx, it's pretty consistant with around 24-26 for mixed highway/city driving.
#10 of 40 Re: '07 mileage figures, anyone? [kurtamaxxxguy]
Sep 19, 2006 (12:56 pm)
It is possible that the new engine doesn't do as well with the extra weight and taller gearing of the Maxx as the old LX9. That mixed with altered EPA guidelines and then the extra load of a p/s pump on the 07 models probably accounts for the decreased mileage.