Sooo... my car absolutely blows on gas. I average about 26 MPG on the highway driving with as light a foot as possible.

I am getting 15 MPG or less if I am under load in the low RPM's.

I had asked Vince from Trifecta if this is something that a tune could fix, and his response was that probably not alot and indicated that the 3" straight pipe might be hurting my low end torque as well as MPG's due to not having enough back pressure.

Does that make sense? I bought the car with the pipe on it. Would it make sense to switch over to a smaller diameter exhaust?

I would love to hear some opinions on this because I drive 112 miles a day for work and was really hoping this car would net me around the same mileage as my SS/SC did.

 

Im tuned with just a muffler and can get 35mpg on the highway. When i got tuned my mpg increased.

 

And thats about what I was hoping to get, or at least above 30. But my question is is the straight pipe that came on the car killing my MPG's?

 

It might be that and the intake. A tune would help you with that.

 

There is no way anyone is getting 35 mpg in an SS/TC, unless you are coasting downhill at 55 mph. So you are saying you get 400 miles to a tank?

I typically get 20 in the city, and 24 or so on the highway, hand calculated. Cruise at 80 or so on the highway. I could see 30, maybe, but 35 isn't happening.

Tune didn't change my street mpg at all.

 

I've only gotten over 30 a couple times and never over 32. Usually I'm at around 26-28 on the highway at 75-80. You are going slow to hit 35.

 

I've NEVER gotten 30+ MPH consistantly.. maybe once or twice for a lil bit on one drive(I look at the inst mpg thing) but Neverrrrrrrr on average or if I do the math.. I was usually around 26 hwy an jack **** city

on my last trip from Tx-PA I got 28.1 from TX- NC an 27.5 for the whole trip an thats with a car full of **** tho.. These MPG threads always bug the **** out of me. I've tried tons of **** I've read on here an ecomodder.com an I never come close to the 30 MPG average that was promised to me on my New car sticker

an then there's always that one assclown that comes in after I tell the stories of my frustration with my featherlight foot, an he offers no help.. just wants another venue to boast about trips he's made rediculously fast while getting 85 MPg.... gtfo

/rant

*sigh*.... but anyways tho man.. if you get off it a lil bit, you should notice a difference.. I use cruise when I'm on flat roads.. it seems to help

 

cruise control in my truck helps a huge amount for me. it seems to go into 4 cyl mode more often i can avg 17mpg around town using cruise control highway ive seen 20mpg

 

I have a v6 2000 monte carlo with almost 300,000 kms, it gets better mileage than the cobalt tc

mine is horrible in town and o.k. on hwy

 

HAHAHAHA 26mpg lol don't get tuned for E85 if that is a problem. I average like 22-23 on my E85 mix tune. I admittedly have a very heavy foot though an I very rarely use the cruise control.

 

I've gotten over 400 miles to the tank... almost 450...

 

I have hit 400 on a tank but it was all highway

 

I got almost 400 once at just under 31 mpg. Took a lot of super smooth freshly paved highway, cruising in the low 70s for the whole tank, and some weather luck.

I still call bs on 35 mpg for a tank unless you were drafting a semi at 60 or something.

 

Best I've seen is 31 on long trip doing 70 .

 

I only see 28 if I feather the pedal and am pointed down hill.

So, is the general concencus (SP?) that the big exhaust isnt hurting to bad? Or is that killing me in the lower RPM's?

Remember, I am 95% +/- highway driving with an average speed of about 70 mph.
This is cruising. There is way to much traffic in the commute to have a heavy foot.

 

Does too much traffic mean speeding up and slowing down a lot? Even roads and tires will make a difference.

 

Same vince tuned me Via SoundJunky. I have to say on the highway I get 38MPG at 100KM/Hour

EDIT : 2.4l 2006 Cobalt

 

Most the time you would be correct. In my case, no. I-83 from York PA to Baltimore is a long highway where it is not uncommon for a pretty large amount of traffic to flow at 75-80 miles per hour. There are long stretches of highway with very few off ramps.

 

I get 25 average with a 20 mile drive one way. Speeds vary from a low of 25 mph to 55mph with some 35 and 45's on the way. And i am easy on the throttle and usually somebody's always following too close. If i didn't want my car smashed i'd jam the brakes.

 

better than what i get, i get 19.4 city

 

Are you stock? I am currently GMstg1 I don't know if it supposively goes up with the kit or not though.

 

I got 36 mpg one way on a 250 miles trip and 33 mpg on the way back both going 70 mph. hand calculated.. don't know how you don't see 35. 30-32 mpg is easy on the hwy in our cars unless something is wrong and 34+ mpg if you're trying. that was all stock except GMS1. I've recently got an intake and 3" catback with GMS1 tune and my city mileage hasn't dropped at all (~23 mpg) but haven't been on any trips since the upgrades and I'm sure hwy will be the same, if not better.

 

If i look at the instant mpg im in the high 30s on the highway.

 

Yea, for real. I'm sometimes in the low 40s but I do have a 3" Catback with resonator and muffler.

 

Wow for an instant lol