I'm looking at buying a 07 Monte SS V8 62k miles. Owner quotes 21mpg on highway. Is this normal or low. I was expecting about 28mpg highway. Could the "fuel management technology" not be working and engine always be running on 8 cylinders? Any opinions appreciated

 

It is possible that the owner had dod (displacement on demand) tuned out, its known for causing oil consumption problems. If its not tuned out, then i'd say there could be something wrong.

 

It really depends on how he drives, and what the mix of city/hwy is. If the 21 mpg figure is based off of 100% highway driving, then something is wrong. Either he's driving well over the limit, doing a lot of passing, or the DOD/AFM is broken/disabled electronically. Some people do disable it on purpose when they get a pcm tune done.

I've got a GP GXP, so it's basically the same powertrain. I tend to get 23-25 mpg on my normal commute which is mostly highway, but some city on both ends, plus city driving for lunch. On straight highway driving when I drove it across country during the move, I was able to get 27-28 mpg if I drove reasonably. I bet 30 mpg is attainable if you don't mind going a little slower- but I didn't want the trip to take forever either. Certainly the further you get above the speed limit, the more the mileage tanks.

I will say city is pretty miserable. I tend to get mid teens in pure city driving.

Realistically though, if gas mileage is up there on your priority list, then buying a full size V8 car may not be the best idea.

 

You can check and see if it is going into 4cyl mode as it will tell you which mode you are in 8cyl or 4 cyl.
21 hwy is a little low considering i have dod tuned out and still get 25mpg on the highway. i think its time for a tune up

 

Thanks Guys! Yes Bumpin, milage is a priority but if the Monte does what it is designed to do, that's fine with me. For 21 mpg highway I have lots other choices. This particular cars owner is the 2nd or third so I don't know the history and the 21MPG I think is out of line. The car is quite far away from me so I'd like a good chance of it being right. Thanks Guys

 

If gas mileage is a priority, you probably shouldn't be getting a v8 anything...

 

If I'm asking of a car with 62k miles on it only to do what was designed and built to do and it cannot, perhaps the car is not for me. A 305hp late model Camaro will do nicely.

 

I DD one of those, and you might not like the MPG on that car either

 

I get really bad mileage.
I had the DoD tuned out after the transmission re-build.
I thought we all got bad mileage, but all you guys who complian about bad mileage, get way better than I do.
And the Camaro also eats gas, but that was expected

I saw a bumper sticker, "Thanks for buying Hybrid, I need Your Gas"

 

I can average 24+ with my dod tuned out on the highway but I do a lot of city driving so it averages out to be 18-21 overall per tank with 91 octane