Two things thats been confusing me a tad lol...

a) I know there are some complaints about the fuel gauge being inaccurate and the like... but does this make sense??
I drive the car fairly hard - novelty is still there - and most of the driving is city driving...
2007 chevrolet cobalt ss/sc - 5300 km - stage 2, gmpp intake/exhaust, summer tires... average temperature is roughyl -3 to -5 celsius...

I get roughly 360-380 km for a tank of gas before it hits the empty line and most of the time the fuel economy claims 10-11 litres/100km....

When I go from the empty line to full and i overfill the tank by roughly .50 cents worth..., it takes roughly 42 litres.... from what I was told, its supposed to be roughly 50 litres + resevoir...

Does this sound right??? is this related to the TSB about inaccurate fuel milage??



b) the sunroof is great.... but when driving anything more then about 40-50 km/hour wind noise is horrible... is this common?? is there a windscreen I can purchase that would nearly eliminate it?



c) finally, when you guys are driving behind larger vehicles... have you noticed that the car seems to wobble?? kind of like it cant handle the drafting?? (and im not even getting that close to the vehicle in front of me)...


Thanks for any/all responses!!
Matt

 

The sunroof on our cars is horribly made. Any wind makes it rattle horrendously.

 

the reason your car shakes when drafting is because it was made to lead, not follow. stop looking at other tail lights and start showing them yours. j/k the problem with drafting is that you are not getting enough airflow for the spoiler to generate enough downforce to keep you planted firmly on the road. the Cobalt is horrible for understeer. eliminating the force needed to generate downforce will make you ride higher, which in turn will make you wobble.

as for #1, if i knew the conversions to american i could help. other than that, i'm lost.

 

You're joking about the spoiler comment right?!?! LOL! That spoiler is 100% for appearances only..... AND WTF DOES UNDERSTEER HAVE TO DO WITH AERODYNAMIC DOWNFORCES?!

 

yeah i can understand that the spoiler is more for aesthetics but that sucks that we cant create downforce enough to prevent wide to side wobble....

what about the sunroof wind-screen or the fuel gauge ?

 

I'm getting the same fuel mileage with my 07 SS/SC. I usually run about 10.5 L/100kms. As for the wind noise, I'm sure there is a company that makes a wind deflector for out car. I'd say AVS most likey does.

 

1. That mileage is because of the rich tune that GM gives the Stage II cars. Get a good tune and you should see your mileage come up.

2. Sunroof...don't have any problems with mine so can't help you out there.

3. My car does the same thing. I also notice when there is a good side wind the car moves quite a bit. I had a Matrix before and it did not move that much...but I am lowering the Cobalt now so maybe that will change it since the center of gravity will be lowered on the car. Who knows.

 

The "richness" of the GM Stage 2 tune that you are talking about really only applies to when the car enters PE mode (ie. WOT). I doubt he's got the throttle over 50% when he's cruising so that explanation doesn't really work. The MAF values that stage 2 uses are pretty close to what they need to be, not saying that a few adjustments wouldn't help but it's not really from what you're thinking. However, there is a noticeable decrease in mileage to be had with stage 2 due to the smaller pulley size since the supercharger is now being spun faster at all RPM's.

I also don't notice any abnormal wind noise from my sunroof, perhaps there is an issue with alignment on yours?

 

Even when staying out of boost I saw a decrease in mpg though. It would be nice to have a performance tune and a 40 mpg tune >.<

 

well, to be honest, i was expecting a lower milage number then a stock ss/sc...
im more or less referring to the low fuel notice and how at the empty line it only takes 43 litres to fill whereas I read up that its a 50 litre tank...

Matt

 

If your car is wobbling, then you're not drafting........you're sitting in the other car's turbulence which is not the point at all of drafting.

 

Yeah it just dawned on me that I was most likely in the turbulence section and wasn't close enough to be considered drafting....

any other comments on the other subjects??

I looked at AVS and there is no sunroof windscreen designed for the cobalt althought they have universal ones in different sizes...

what about the fuel situation??? 43 litres sounds very low considering several websites both advertise 13 gallons/50 litres...

Matt

 

if you want mileage you cant drive like you are driving.

the sunroof will never be silent when open.

getting blown around in another cars draft is pretty normal.

 

I've never heard of them having 50 litres. Mine takes around 42-43 as well.

 

No, I'm not joking. This si as per the Grand Am Series Cobalt teams. All of them have dropped the spoiler when racing because it creates too much drag. For example, at Miller Motorsports Park in Tooele, Utah where the final race is held there is a 9/10ths of a mile straight. They said the spoiler slows them down about 3mph. The decided to go with this instead of using it to create downforce which helps in corner due to the Cobalts natural potential to understeer. Downforce helps reduce lift created by the air that flows under the car. Because the car is "floating" on top of that air. It doesn't want to turn as readily. If you don't believe me about the Cobalts understeering problem I recommend that you go do some research. Consumer Reports is a good reference for what I'm talking about. It flat out states it. BTW, I'm in no way saying that the spoiler completely eliminates the understeer problem. It was meant to help the car, not solve all of its problems. I also have the high rise spoiler too.

 

a) The TOTAL capacity of the fuel tank would be 50 litres. When you get to around 42 litres or so the low fuel warning will come on - this is by design. Also the DIC is not 100% accurate at calculating miles per kilometer. I would say it is about 80 - 90% accurate based on my own calculations. Also, if you are only getting 360 - 380 km per tank you must drive the car pretty aggresively.

b) I do notice a little wind noise if I have the cover open, but it isn't bad. You may just need to get the sunroof adjusted.

c) You tires have alot to do with how much side to side force causes your car to wobble. If you get some tires with stronger sidewalls you can eliminate some of that wobble.

 

I have to admit i have been a tad heavy on the throttle as I have only got the car roughly two weeks...but i do alot of highway where i am not hopping on it...

As for the low fuel warning around 42 litres.... I get my warning between the 1/8th and empty mark.... BUT.... I wait till its on/below the EMPTY mark and thats after driving for roughlt 60 km from when the low fuel warning comes on.

When I fill up the tank when its at/below the empty line (by roughly 1 needles worth)... it takes a total of ~43 litres to fill that includes overfilling the tank by a little bit...

So, If I was to drive even more... that would mean I would be driving on 7-8 litres WHILE its below the EMPTY line...

Does this sound about right???
According to this forum, and Autos.Msn.com... the cobalt has a 13 gallon tank (50 litres)

 

You can drive the car for quite awhile after it hits 'E'

Dont push it too hard though, I've run out of gas before

It sucks!

 

I'm planning on getting a canister of gas and keeping it in the trunk for one of those "worst-case scenarios"

 

While that sounds like a good idea I would have to suggest against it. Unless you drive with the windows down all the time you could get fumes built up in the cabin and that would not be good for many reasons....

 

Why would u wait so long to fill up? Isnt it bad to do that?

 

I'm pretty sure that's hard on the fuel pump to be running on empty all the time.