Last post on Oct 01, 2012 at 9:27 AM
You are in the Chevrolet Aveo
What is this discussion about?
Chevrolet Aveo, Fuel Efficiency (MPG), Hatchback, Sedan
#259 of 268 Re: Gas Mileage [randydriver]
Mar 29, 2010 (8:06 am)
I drive a 2009 Chevy Aveo LS, 4 door, sedan, 4 cylinder 1.6 liter Ecotec engine. It has a manual transmission, 5 speed.
I get 42-46 driving 65-70 mph on interstate or highway all the time since buying it, checked it numerous times on long trips. I have never got below 33 mpg on a tank of gas. Driving in city usually ranges 33-35 mpg, city and highway usaully average 38-40 mpg on tank of gas. That would be like 60-70% highway and 30-40% city driving. Live in St Louis, MO area.
#260 of 268 Re: Chevrolet Aveo Real World MPG [norm116]
Aug 30, 2010 (2:44 pm)
try replacing the spark plugs. the are installed by a machine and can break. My brother had similar problems with gas mileage on another make. Took it back to the dealer many times, only to be told there was nothing wrong. Finally changed plugs and gas mileage increased to normal expected range. The plugs were cracked from over tightening by the factory robot. My daughter has a 2009 Aveo 5 speed and it gets rated gas mileage.
Good luck and hope it works. Can't hurt to try it.
#261 of 268 Re: Chevrolet Aveo Real World MPG [robie_dobie]
Aug 30, 2010 (6:25 pm)
Didn't think it possible, but on my most recent tank of gas, after a fresh oil change, I got the lowest mileage ever.
16.5 mpg.... on this tiny little pinto of a card. 16.5 mpg and I driver her very softly.
16.5 mpg is less than I get in my Santa Fe.
#262 of 268 82000 mile average
Sep 08, 2010 (9:09 am)
My 82000 mile average is 39.97 mpg in mixed driving. I was hoping to stay over 40 but a new timing belt at 59995 seems to have cut down the mileage a bit. I will be going on the 3rd set of tires soon.
Sep 08, 2010 (9:15 am)
I just bought an 2008 Aveo with a 5 speed i get bete=ween 35 and 37 MPG running 60-65 I am going to get a K&N air intake hoping to get 39-40 at 55
#264 of 268 Important: Why your Aveo automatic gets poor city MPG
Feb 15, 2011 (2:36 pm)
#265 of 268 Important: Why your Aveo automatic gets poor city MPG
Mar 18, 2010 (7:54 pm)
Our 2009 Aveo5 is only a few months old with less than 2000 miles on it. We like the car very much except that the city MPG has been disappointing. The city EPA estimate is 25. The best we have been able to get is 22 MPG. After installing a scan gauge and driving very conservatively I was determined to find out specifically why the fuel economy is so inadequate.
After considerable research I found the transmission is made by Aisin, a Japanese manufacturer with a good reputation for quality transmissions. It is an ordinary 4 speed, with no overdrive. The same transmission is found on all Aveos made from 2004 to 2010. I recently found the service manual for this transaxle, Aisin 81-40LE. It can be found on-line at: http://www.anagabriela.ro/.../2.%20AISIN%20AUTOMATIC%20TRANSAXLE.pdf
The graph on page 5A2-12 shows the manufacturer’s specification for shift points. (The graph is stated in KMH, so I’ve converted the figures to MPH for this discussion.) The graph shows the shift points will vary somewhat according to the TPS (throttle position) reading. On my car a scan gauge registers the TPS reading at idle at about 16; very conservative (slow) acceleration would be about 25; brisk or above average acceleration would be about 35 TPS.
According to the graph, at 25 TPS the shift points should be at about 11, 20 and 27 MPH. At 35 TPS it should shift at about 12, 22, and 32 MPH. I compared what I am actually getting on my car, at about 35 TPS, which would be considered average or brisk acceleration. I found it actually shifts at about 15, 25, and 45 MPH. In other words, the upshift into the highest gear (fourth) is much too late. Most 4 speed transmissions typically shift at approximately 10, 20 and 30 MPH. The delayed shift into high gear at around 45 is a major reason for delivering poor city FE. I live in suburbia. On major roads, typically the speed limit is 40. Unfortunately, when there is traffic it is impossible to break 45 – thus the car is spending most of its time in first, second and third gears at best, and it virtually never goes into high gear, which would yield the best fuel efficiency.
The transmission shift points are entirely determined by an electronic module called the transmission control module (TCM) which was designed and pre-programmed by Chevrolet. The shift points for which it is programmed are widely different than the documented specifications of the manufacturer, Aisin. I visited a Chevrolet dealer and spoke with the service manager to see if the TCM could be reprogrammed. He told me that they could do nothing to change it, unless Chevrolet had issued a service bulletin update for the program (which is has not done in the past five years that Chevy has been using this transmission on the Aveo). In other words, unless and until Chevy engineering rewrites the programming of the shift points and offers it as an update for dealers to install, nothing can be done to rectify the existing discrepancy. I then visited my local transmission shop (AAMCO) and asked the same questions. They confirmed that there is no way to reprogram the TCM unless Chevrolet rewrites the programming for it.
From what I have read on the web this is a very common complaint for Aveos. Most owners are unaware that their cars are late in shifting into fourth gear and frustrated with their poor city mileage. Seeing that there is documentation supporting the fact that the TCM programming of Chevrolet is greatly divergent from the specifications of Aisin, the manufacturer of the transmission, I believe Aveo owners have a valid grievance against GM and should press to have the situation rectified.
Who can we complain to? How can we unite to complain effectively and have Chevrolet correct this situation?
#266 of 268 Re: Important: Why your Aveo automatic gets poor city MPG [barkydog]
Feb 08, 2011 (1:56 pm)
Somehow, you link to the transmission PDF it truncated: Could you send it directly to resqdogz at gmail.com , please?
I, too, sufffer from abysmal fuel economy with my 2008 Aveo LS 5 door...
#268 of 268 Re: Important: Why your Aveo automatic gets poor city MPG [barkydog]
Oct 01, 2012 (9:27 am)
barkydog: Thanks for your work on this! I guess I will need to try to go slower, or faster. Really can't go over 45 in town though, so would have to go slower. Probably not worth it. Chevy should have fixed this long ago. Typical lack of true concern once they sell a car.