Good Day All,

I own a 2005 Monte Carlo SS/Supercharged 3.8 liter. Great car! However the gas mileage leaves something to be desired. I know the supercharger is drawing more fuel into the engine, but at crusing speed (65 - 70 mph) the motor should flatten out as no additional power is required. Earlier models had a computer which would lean out the fuel usage when it wasn't needed. My question is, what modifications can I make to increase full effecincy (beside removing the supercharger)? And no, I don't put it to the floor when I drive at least not always. Any useful or humorus comments welcome.

 

Have you checked the condition of the air filter recently?

A dirty filter will affect mileage.

 

i just bought an 04 s/c monte and took it for a ride yesterday since it was nice... the fuel monitor in it says im gettin like 19 mpg and i was on the highway... i was also under the impression that these cars got WAY better gas mileage, it just feels sluggish goin down the road, i was kinda let down myself

 

I'm with rj on this issue.

My Air Filter was never replaced by the PO and I got it with 68,000 on it. When I pulled the Air Filter it was so caked with crap that it wouldn't vacuum or even knock-off the front of that Filter element.

For the cost of a new Filter, I'm replacing that thing as soon as the good weather finds New England and a couple of times over the Summer. I'm making sure that the car can breathe!

It sure couldn't when I got it!

 

i dunno i thought that too and pulled out the filter yesterday to find that it has a new k&n in it, nice n clean

 

I noticed that my supercharged '04 is very thristy also. And I don't get a chance to gun the engine with all the congested roads around here. I installed a brand new K&N filter when I bought the car,and maintain it regularly. I think this is just an inherited characteristic of the s/c engines in the 04's and 05's.

 

Welcome to MCF Randy!!!

What kind of gas milage are you seeing? That would help a bit as if you were expecting 35 you won't get it.

With all the mods I have done to my car I still get 28 MPG.

For better milage, I would recommend Cold Air Intake and the larger Downpipe with Cat. I was getting about 30 with that.

 

Put either a K&N or a Wizaired cold air intake get rid of the U-bend pipe, and you're milage SHOULD be 25mpg or better. Intake alone is worth 2mpg. If everything is running efficiently, you should get about 22.5mpg stock, unless it's all city driving, OR you're running REGULAR gas instead of premium. OR, you're buying CRAP gas instead of top tier gas. How does it run at idle? MAYBE it needs a can of Seafoam thru the gas tank and "drive it like you stole it".

 

btw, if you are using the DIC to calulate you gas milage, i've found, as well as some others, that it's incorrect. It tells me that I'm getting a good 2 mpg better than what I'm actually getting. Nothing beats a pencil and paper and doing the math yourself.

 

Yep, mine's off too, as is the gallons used, on a whole tank it'll say I've used 2 gallons less than I really have. Wonder why they are all off and by about the same amount. With pen and paper, I average 24-26 mpg (not supercharged, all stock, AC Delco filter - yes, I'm thinking about changing it to a K&N - will it really help?)