[KAS]

My husband recently replaced his 2004 Impala with a new 2007 LT. He used to get as much as 35MPG. Now after 4,000 miles in the new one and trying different fuels, we're hard pressed to get 25 MPG. They both have V6 engines. It's so bad we even took it to the dealer to get checked out. The mechanic said there was nothing wrong with it.

Does anyone have any suggestions? What kind of mileage do you get with your 06 or 07 Impalas?
It is the same size engine, not sure if Chevy changed anything about it with the new model. I also know that E85 fuel will hurt economy a lot, so we've tried regular unleaded/premium etc.
I should also specify that 25 is the max we can get on the highway and not an average over an entire tank of gas.

 

[John L]

The mileage you are getting sounds like a 3.9 v6 they not known for mileage. Most of the LS and 1Lt impalas get 32 they use the 3.5 v6. I don't know for sure but your mileage does sound low to me have them check your o2 sensors to see if they are reading correct I had one go bad but it didn't trigger my check engine light once it was replaced I got better mileage.

 

[BOB]

The mpg difference is due to the type of fuel you are using.
E85 does not burn as efficiently as tradition gasoline. Recent tests by the National Renewable Energy Lab on fleet vehicles owned by the state of Ohio showed about a 25% reduction in mpg comparing E85 operation to reformulated gasoline in the same flexible fuel vehicle.

I replaced my 03 Impala with an 06. Both vehicles have been flawless. I have not tried the E85 myself (feeling guilty now), but I am getting slightly improved mpg with my LT2. My 03 was an LS with a 3.8L engine that got about 29MPG hwy. I suspect your 04 may have had the smaller 3.4L V6 engine with better MPG but less power.

IMO, you have purchased a great car and are getting respectable fuel economy considering the power, weight, and fuel choice.

: )

 

[Melissa T]

25mpg sounds right for an impala. is it the same v6 engine?

 

[1chance]

yes 25mpg sound pretty accurate if you want to try to stretch that a bit then use cruise control more. the 06-07 models are designed to break the cylinders down to a minimum when there is no speed increase. when cruise is engaged a fuel tank lock mec is activated within the cars computer output. which basically tells the engine how much gas will be used to go the distance. your fuel level will rise at that point giving you a estimated 450 miles per topped tank of regular gasoline. Chevy has given all its cars high duration so play with that fact a little