I have an HHR (love it) with 2.2 and of course it is same drive train as Cobalt. I am going to dedicate some money to making it get better gas mileage. I would like your opinions on what is the best things to do and what actual mileage gains to expect.
Basically if you get better air flow into and out of the motor with the correct fuel mixture it will be more effecient and better performance to.

I know that keeping your foot out of it will help my mileage but what I am asking about here is mechanical improvements. Also I am not going to "Hypermile" and run 43 MPH in the fast lane or draft a big rig. I drive normal and do not accelerate too hard but I do cruise at a decent speed on the highway 65 to 80.

What I am thinking is
1. Axle back exhaust CGS.
2. Lowering car 2 inches Goldline
3. K & N filter
4. Trifecta tune

On the above items is there anything else better? Why is it better? Any other suggestions?
I am willing to spend some money but of course do not want to waste money and want to get the most Bang for the Buck.

Thanks in advance, Curly

edit. forgot you had an hhr. woops

It does not matter if I have an HHR, the drivetrain is exactly the same. If it helps your gas mileage it will help mine.

Nobody has any opinions on improving mileage on the 2.2?
The drivetrain is exactly the same and the weight of the vihicle is close.
Somebody has to have real world experince improving the mileage.............

turbo it

little button in the upper right hand corner of your screen called 'search' will get you some answers. Sorry, but this topic has been discussed to death.

And just an fyi I'd stay away from any oiled filters like K&N they have been know to cause problems with MAF sensors in our intakes, use a dry high flow filter and it will work fine.

Here are my mods and results so far.
1. Lowered the car 2 inches
2. Front Air Dam
3. Taller tires, Soltice wheels
4. Airaid intake filter
5. 2.4 Intake manifold.
6. 2.4 Exhaust including downpipe and cat. Then put a Cherry Bomb Vortex muffler

Mileage is up from 21 in the city to 25-26, on the highway @ 70 it was 31 now it is 36 MPG.

My next mods will be a 2.0 ported exhaust manifold or header and a Trifecta tune. With that I expect to get 28 in the city and 40 highway @ 70. Considerably better than 21/30 EPA rated and what I was getting.

Also the car handles and rides MUCH better now with the springs and it sounds better with the intake and exhaust.

By taller tires and solstice wheels do you mean that the overall radius is bigger? If so you need to get your speedometer/odometer re calibrated otherwise your number are useless.

Actually mileage is better than it says because my speedo is a little low now meaning my car travels about 4% farther than the speedo reads. I did not recalibrate my speedo or add anything to my numbers so it is better than it says.
In any case mileage and performance HAVE improved noticeably and to top it all off the car looks, handles and rides better.

Freeing up the flow (in and out) was likely the biggest factor. The 2.2's don't have the most free flowing setup out of the box. Taller wheel tire combo, same effect as taller gears....less revs per mile, less fuel required.

Lowering, less wind resistance (a tiny bit perhaps but less), can't hurt. And as you pointed out, looks and handles better :)

Performance....kinda hard to say without either dyno numbers or time slips, before and after. If it sounds faster (and I'm guessing it does :cool:) it will almost always "feel" faster. Those taller tires are not going to help performance but they likely are hurting less than freeing up the flow helped so...net gain would be my guess.

Even if you gained zero performance, you did gain mileage, ride, handling, and looks......not a bad return I'd say ::cssNET:

The taller tires did help mileage but hurt performance an equal amount. With my other mods it is still a little faster than stock cars, in a drag race they pull on me a little at first but then she starts running and passes them at higher speed.
Then I am building my car more for mileage and one way to do that is free up the intake and exhaust.

Dynos and time slips are not always the final answer when comparing mods. My drag race car will run 2 to 3 tenths difference depending on weather with no other changes. You get a time slip one day for a baseline then make some changes and come back next week under different conditions you really do not know if or how much it helped or hurt.

....8>< snip....
Dynos and time slips are not always the final answer when comparing mods. My drag race car will run 2 to 3 tenths difference depending on weather with no other changes. .....8>< snip.....

True enough, time slips from different days / tracks can't be compared directly.
Dyno runs should be comparable if run on the same dyno and the proper correction factors are used.

Guess what I am really saying is that the "butt dyno" is very easy to fool :)

[QUOTE=The Curly One;3336679]
3. Taller tires, Soltice wheels
QUOTE]

Is any of your testing back to back?
I would argue that you got equal or worse milage with 18" and taller tires. In general they are heavier, require more force to accelerate, and they have more rolling resistance.
However if you do mostly highway driving they should give you slighty better mileage.


Do you have a Cobalt or a HHR? How well do the solstice wheels fit? What size tires did you use?

I am looking into getting some Trak Lite rims as they are only 10lbs a piece compared to the stock steel ones that top the scale at around 22lbs a piece!
That will drop 48lbs right there.

I might get a carbon fiber hood to look nicer and lose a few more lbs.

Many of the bolt on mods can help, but can also make mileage worse as you are usually tempted on going faster. It gives the ability to use less gas, but... it also gives you the ability to use more gas too.

Replacing the stock seats with light weight race seats helps lose weight too.

Just some ideas...

4. Airaid intake filter
5. 2.4 Intake manifold.

an intake, such as injen, will increase mpg efficiency. the 2.4 IM actually decreases mpg bc of the loss of low end torque.

if i was you i would not get a trifecta... not saying there bad just saying mpg can be increased even more with a tune specificly for ur car( custom tune/ a tuner in ur area) you can lean it out a little more because trifecta wants to keep it safe( there tunes are 50 state usable ) meaning when u get it it could be perfect or ritch because they dont want to send a lean tune ( could cause a blown motor) they will ritchen it up...

long story short i would get a custom tune and u would get better mpg than any canned tune.


u could also do a weight reduction( there is a thread on it.. very nice write up actuily... http://www.cobaltss.net/forums/showthread.php?t=110529

i know some of its extreme for a non track car but it tells u what kinda weight u will be sheding taking it off pice per pice.