2005 Cobalt 42-44 mpg consistent
 

We drive 67 mile commute LA county; recently replaced one tire and this week our average entire week is 44.0 mpg, previous weeks was coming in more like 42. We still plan to replace plugs and wires, buy KN filter, and replace all four tires in a few months with Michelin Eagle or something equivalent or better. Anyone with tire experience we would like to hear about what gets the best mileage, and what inflation you run at. We coast about six miles continuously at one point every day...but if you are thinking, we climb the same hill going home so it averages out over time. Stop lights still our worst enemy, we make some and miss some and usually in traffic so cannot always time the takeoff and avoid stopping.

But with two drivers and commute traffic both ways, a car rated about 30 is doing pretty well in my book. Internal car gauge is confirmed by actual gas purchases to be within 1 mpg of accurate.

Great job! Is that an auto or manual? I'm going to guess manual from the numbers. I also have a huge hill to traverse (climb to work; coast coming home) and I was able to get average over 46 mpg in my 2006 manual Chevy HHR (similar Ecotec engine as yours) when I was doing all-out hypermiling.

It's a manual transmission...
 

we would like to think the car is capable of about 45-46 with the right tires. Some depends on the traffic, of course, some days we go up to 5-10 miles stop and go, other days we pretty much cruise to and from work. But 44 for the whole week has been pretty impressive. I was getting 2 1/2 trips in my son's 97 Monte Carlo (17 gal tank) before we started hypermiling the Cobalt, which as 13.2 tank and we are getting close to four days now. My son has done some "playing" with different speeds and the internal gauge and it shows that it peaks around 47 mph in fifth gear, at about 52 mpg, and drops nearly 1 mpg for every mph up to about 55, which if you are doing the math is still 40+ mpg at 55. :turtle:

Congrats!

FYI, don't buy a K&N filter if your sole motivation is fuel economy. It won't make any difference. There's a good reason the company itself does NOT promise MPG gains in its advertising.

wolfpuppy -

Welcome to EM! In terms of tires you can go to tirerack and search for tires for your car and select "Low Rolling Resistance" only. Here is what I find for your car :

Tire Search Results

I went one-size-up from stock when I got new tires :

http://ecomodder.com/forum/showthrea...ires-2642.html

I didn't try two-size-up because the weight of the tire went from 1+ lbs to 2+ lbs. You can find the weight of the tire by looking at the tire specs :

Continental*ProContact with EcoPlus Technology

Here is the same tirerack URL but isolated for Continental tires only :

http://ecomodder.com/forum/member-cf...ontinental.png

I actually (failed to document that I) switched from the ContiProContact to the ContiProContact with Ecoplus technology maybe one or two years ago. I detected *no* difference in MPG, but I was going from low-tread tires (= high LRR) to new tread, so I did not expect any difference.

CarloSW2