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Adjusting current designs in hope of wringing an extra_MPG out. (http://www.msnbc.msn.com/id/26395430/)

http://www.cleanmpg.com/photos/data/501/2008_Chevrolet_Cobalt_xFE.jpgAP - Aug 25, 2008

2009 Chevrolet Cobalt – 25 city/37 highway and 30 mpg combined on the 08 EPA.

GM is heading in the right direction with taller geared vehicles. Now they have to work on the city numbers :) -- Ed.

DETROIT - In a normal year, the 2009 Chevrolet Cobalt wouldn't be any different than the 2008 model, save for a few minor cosmetic changes. But this is far from a normal year.

With gasoline still hovering around $4 per gallon, many manufacturers are making far more than the usual tweaks to cars and trucks between model years to squeeze out one or two more miles per gallon and catch customers who increasingly rank fuel economy as a top factor when buying a vehicle.

Automakers say you can expect more of the same as they roll out new technology without waiting for full vehicle updates.

"Fuel economy is very important," said Greg Peterson, General Motors Corp.'s vehicle performance manager for compact cars, including the Cobalt. "That is one of the drivers in the changes that we made."

In the high-mileage version of the Cobalt and its Pontiac sister, the G5, engineers varied the intake and exhaust valve timing to make the 2.2-liter four-cylinder engine burn fuel more efficiently. They arranged with Goodyear Tire & Rubber Co. for tires with lower rolling resistance, and they changed the gear ratios of the five-speed manual transmission so the engine revs more slowly at highway speeds… http://www.msnbc.msn.com/id/26395430/

And when new models come out, look for more dramatic improvements. GM, for instance, says the Cruze, the Cobalt's replacement coming in the second half of 2010, will get around 45 mpg on the highway.

That, if true, would be impressive. :eek:

The Cobalt's published fuel mileage figures are actually better then my Camry.

The Cruze is, essentially, the Chevy Volt without the electric motor components and the fancy accessories. This is a positive direction for GM.

This is good news, in a sea of bad news for the big 2.5. I look forward to seeing more existing models get modifications done, even if small. I noticed Wayne's bolding of the line in which the higher gears rev more slower and I thought about the 2009 Honda Fit. I really expected the 2009 model to beat out the 2008 MT in FE but alas I was wrong. Hope Honda fixes that for the next year at least, like how the American car companies are currently doing.

-Jose

They added...

Something similar to VVT-i
LRR OEM rubber
Taller gears

And it gets *one* (1) mpg highway better per the EPA?

Something very wrong here.

Hi Ben:

___That is over the 08 which was already tweaked for another 2 or 3 IIRC?

___Good Luck

___Wayne

The other day I rented a new ford focus and loved the taller gear. I was at 1500rpm going 55mp/h and 2500rpm at 75 MPH!

Driving with other people, not caring at all about FE, using the air, but still driving smoothly compared to other people, we easily got 40 MPG.

Just how tall is "taller". Voodoo 22, above, said a Focus he rented turned 1500 RPM at 55MPH. The article does not say, possibly purposefully. That truly is good, if it is a manual transmission. It beats the RRSB Saturn I commute with soundly. Combined with good sound hypermiling techniques, someone could really keep themselves out of the poor house with gear ratios that tall.

We here at CleanMPG.com should require of cars we are writing about the specifications required to make a car a good hypermile vehicle. The RPM's it turns in high gear at 60 MPH is one such critical number!

As more people hypermile, perhaps they may think of us when making changes.. I think i could get more than 1-5 mpg's. It is sad that they fought cafe's so vehemitly, and now can squeeze more so easily!

Just how tall is "taller". Voodoo 22, above, said a Focus he rented turned 1500 RPM at 55MPH. The article does not say, possibly purposefully. That truly is good, if it is a manual transmission. It beats the RRSB Saturn I commute with soundly. Combined with good sound hypermiling techniques, someone could really keep themselves out of the poor house with gear ratios that tall.

We here at CleanMPG.com should require of cars we are writing about the specifications required to make a car a good hypermile vehicle. The RPM's it turns in high gear at 60 MPH is one such critical number!

From chevrolet.com, the ratios for the Cobalt, it looks like they have a slighly different set of ratios and final drive:
5spMT - - - 5spMT
RPO F35 - - - MM5
1st 3.38 - - - 3.58
2nd 1.76 - - - 2.02
3rd 1.18 - - - 1.35
4th 0.89 - - - 0.98
5th 0.70 - - - 0.81
Axle 3.82:1 - - - 3.94:1

According to tirerack.com, the OEM tire is the ContiTouringContact AS, 195-60-15. Lists 850 revs/mile (rpm @60mph)
So 850 x 3.82 x 0.7 = 2273 engine rpm
vs 850 x 3.94 x 0.81 = 2713 engine rpm
Ironically, the 4sp has a top gear of 0.68 and a 3.63:1 axle, so (850x0.68x3.63) = 2098rpm
Looks like all they did is drop the ratios a bit to get the MT version to within 200rpm of the AT version.

When it was said that, "engineers varied the intake and exhaust valve timing to make the 2.2-liter four-cylinder engine burn fuel more efficiently", I'd guess that's the classic "cam job", where they vary the lift and duration to make more low end power at the expense of high end breathing. This would be necessary to get away with the taller gearing without much change in acceleration.

I am also seeing the 2009 Cobalt A/T at 24/33 versus 22/31. No XFE badge on them (yet), but considering how many of them are selling, the +2mpg in both city and highway is at least a step in the right direction.

I have a link to an inside webpage for GM dealers that has ordering pages. I see that the 2009 Cobalt has several "new" features to boost FE. One interesting weight saving is the removal of the spare tire and jack. They have a can of inflat-o-goo in its place. Seems like they are prepared to sell it as "additional x cubic feet of space beneath the trunk floor", too.

As noted, the 2009 Cobalt is rated 25/37. That is under the 2008+ EPA, so it'd be good for close to 50mpg in the right hands. For a 2.2L engine in a 3000 pound car that sells for an average price of $13k-$15k, I think that's pretty darn respectable.

As more people hypermile, perhaps they may think of us when making changes.. I think i could get more than 1-5 mpg's. It is sad that they fought cafe's so vehemitly, and now can squeeze more so easily!

Kinda makes you wonder why they were fighting so hard...

Kinda makes you wonder why they were fighting so hard...

This is just a general guess, but I would suspect that the fighting is due to the fact that the CAFE numbers were at odds with what the public wanted to buy at the time. You can have any of three things in varying quantities, based on design compromises, and adding to one will take away from the other two:
1 - Cheap to build
2 - Good fuel economy
3 - Fast and Furious
So for an automaker, #1 gets top priority. If the public wants more of #3 (fueled by the auto press), then #2 suffers. Suddenly, #2 is getting top billing, as gas prices have doubled in a the last few years. So all the automaker does is change the compromises to give you more of #2 while taking away some of #3. In the case of the Cobalt XFE, the advent of the turbo SS model means they can refocus the LS/LT as high FE commuters and low-cost family cars and sell the SS to the people who absolutely must reach 60mph by the far side of an intersection.

Now that the public is generally demanding better FE, the fight against CAFE will remain although for a different reason. The short time frame is what is killing them now. That is another compromise they have to contend with - "You can have it at low cost, next week, or done well - pick any two".

Hi MaxxMPG:

___When I posted this, I was looking over the build specs of the 2.2L ECOtec but there was nothing differentiating the xFE from the 2.2L used in previous years. I also could not find a thing on the 09’s ratios on the media site either :(

___2,200 RPM is getting close but there is some more room to play with yet ;) Like a real wide spread 6-speed and get rid of that POS small Auto used in the Cavalier and than the Cobalt. It has been the scourge of GM for 10 + years.

___Good Luck

___Wayne

This is just a general guess, but I would suspect that the fighting is due to the fact that the CAFE numbers were at odds with what the public wanted to buy at the time. You can have any of three things in varying quantities, based on design compromises, and adding to one will take away from the other two:
1 - Cheap to build
2 - Good fuel economy
3 - Fast and Furious
So for an automaker, #1 gets top priority. If the public wants more of #3 (fueled by the auto press), then #2 suffers. Suddenly, #2 is getting top billing, as gas prices have doubled in a the last few years. So all the automaker does is change the compromises to give you more of #2 while taking away some of #3. In the case of the Cobalt XFE, the advent of the turbo SS model means they can refocus the LS/LT as high FE commuters and low-cost family cars and sell the SS to the people who absolutely must reach 60mph by the far side of an intersection.

Now that the public is generally demanding better FE, the fight against CAFE will remain although for a different reason. The short time frame is what is killing them now. That is another compromise they have to contend with - "You can have it at low cost, next week, or done well - pick any two".

Was thinking about this this morning, seems to me that to a large extent the public chooses among what is available. Which gives false signals as to what the public wants. Two illustrations:

(1) Mfrs make FE models which are also real cheaply made. They don't sell because public doesn't want to drive low quality vehicles, not because they don't want FE. So mfrs decide public doesn't care about FE.

(2) In 2003 I decided it was time to replace my beloved 1994 Honda Accord Wagon. Wanted something with a long roofline to haul boats, MT, high reliability, and good FE. Volvo wagons too expensive for me, not available in MT. Audi way to pricey. VW Jetta and Passat Wagons had poor reliability ratings. No more Camry wagons. Honda CRV was only Honda "wagon", and its roof bars were unsuitable for hauling long boats. So I ended up with the Subaru, which fit on every point but the FE, which even with the basic 4 cyl was ca 4mpg less than my Accord Wagon's. If something with better FE had been available I would have bought it for sure.

Mfrs may be diabolical or misguided, maybe not, but for sure they build what they think they can sell and then market like crazy to persuade people that that is what they want to buy.

Hi MaxxMPG:

___When I posted this, I was looking over the build specs of the 2.2L ECOtec but there was nothing differentiating the xFE from the 2.2L used in previous years. I also could not find a thing on the 09’s ratios on the media site either :(

___2,200 RPM is getting close but there is some more room to play with yet ;) Like a real wide spread 6-speed and get rid of that POS small Auto used in the Cavalier and than the Cobalt. It has been the scourge of GM for 10 + years.

___Good Luck

___Wayne

Wayne,
The new 2.2 for 2009 is E85 compatible and has a different RPO code, so it is the same engine, but with a PCM flash, and different fuel system components to tolerate the corrosive E85 fuel.

I am not seeing anything about a new axle ratio for '09, but it wouldn't surprise me to see them drop in the automatic's 3.63:1, as that'd just about match highway rpms as the top gears in each trans are about the same.

With scarce funds and the Cobalt getting sent out to pasture in two years, I strongly suspect the Cobalts will be 5 speed M/T or 4 speed A/T until they go to heaven, where the saints can hypermile them.

They seem to be selling very well, so I think GM is doing a fair job of "doing the best with what you have", selling what has stood the test of time and is cheap to build. The compromises definitely make it a "much less than perfect match" for those looking for the best FE. But since it is selling is such volume, I think that boosting the EPA by a few MPG is excellent, considering that the small gain is multiplied by so many cars. Another consideration is how many people are trading their Trailblazer/Tahoe/Equinox guzzlers in on a Cobalt because Chevy is more likely to take their trucks in trade than a dealer of a competing make. The low cost of the Cobalt takes the sting out of the collapsed resale value of the trade, and so it is doing a good job of getting the guzzlers off the road.

From chevrolet.com, the ratios for the Cobalt, it looks like they have a slighly different set of ratios and final drive:
5spMT - - - 5spMT
RPO F35 - - - MM5
1st 3.38 - - - 3.58
2nd 1.76 - - - 2.02
3rd 1.18 - - - 1.35
4th 0.89 - - - 0.98
5th 0.70 - - - 0.81
Axle 3.82:1 - - - 3.94:1

According to tirerack.com, the OEM tire is the ContiTouringContact AS, 195-60-15. Lists 850 revs/mile (rpm @60mph)
So 850 x 3.82 x 0.7 = 2273 engine rpm
vs 850 x 3.94 x 0.81 = 2713 engine rpm
Ironically, the 4sp has a top gear of 0.68 and a 3.63:1 axle, so (850x0.68x3.63) = 2098rpm
Looks like all they did is drop the ratios a bit to get the MT version to within 200rpm of the AT version.

When it was said that, "engineers varied the intake and exhaust valve timing to make the 2.2-liter four-cylinder engine burn fuel more efficiently", I'd guess that's the classic "cam job", where they vary the lift and duration to make more low end power at the expense of high end breathing. This would be necessary to get away with the taller gearing without much change in acceleration.

I am also seeing the 2009 Cobalt A/T at 24/33 versus 22/31. No XFE badge on them (yet), but considering how many of them are selling, the +2mpg in both city and highway is at least a step in the right direction.

I have a link to an inside webpage for GM dealers that has ordering pages. I see that the 2009 Cobalt has several "new" features to boost FE. One interesting weight saving is the removal of the spare tire and jack. They have a can of inflat-o-goo in its place. Seems like they are prepared to sell it as "additional x cubic feet of space beneath the trunk floor", too.

As noted, the 2009 Cobalt is rated 25/37. That is under the 2008+ EPA, so it'd be good for close to 50mpg in the right hands. For a 2.2L engine in a 3000 pound car that sells for an average price of $13k-$15k, I think that's pretty darn respectable.

Great info, MaxxMPG! Thanks for the calc. ;)

The 5 speed MT turns about the same RPM's as my wifes VW Golf (2550 RPM) making it a "city car" only. I have taken her car to work (my commute is 100 miles round trip, 90 % rural country roads) for a whole week to do my best hypermiling. The best I could do is 42 MPG and I had to do a lot of coasting. It is just geared too low for the highway. But it is quite at home in the city. My wife consistantly scores MPG figures in the mid 30's, at times up to 38 MPG.

So, for people looking for a good city car to keep BP away from their door, this would do the trick!:)

Bob.

I drove a 2008 Chevy Cobalt for 10 days when my partner's car was being repaired after a wreck. It was actually a pretty decent car. We actually ALMOST bought one, but ended up with a Scion because my partner wanted a hatchback.

I drove a 2008 Chevy Cobalt for 10 days when my partner's car was being repaired after a wreck. It was actually a pretty decent car. We actually ALMOST bought one, but ended up with a Scion because my partner wanted a hatchback.

Indigo,
Your assessment of the Cobalt is right on target with what the majority of the public thinks about the Cobalt - "It's a pretty decent car". It doesn't stir passion or win major awards or consistently lead the top of the class. But it does what it does well.

It's a safe buy for anyone who wants good (but again, not class leading) FE at a rock bottom price. The Honda/Toyota alternatives are more in vogue, and (pound for pound and inch for inch) provide somewhat better FE, but they can be tough to find sitting on the lot, and even tougher to wheel-n-deal to a reasonable price. The Honda/Toyota dealers around here are horrible. If they can't get you on the price tag, they will try to get you on the financing.

Based on my informal scan of other cars on the road in my area, I can see that more people are discovering the Cobalt as they trade out of the SUV and into something small. It's still "imported-car capital of the world", but where I used to see Jeeps/Explorers/Envoys, I now see shiny new Cobalts.