My 1989 sse is consistently averaging 19-20 mpg since I have owned it for a year.Bought the car after my fiancee recommended it and after doing research on vehicles.The many happy customer reviews that I came across in my research made me consider a Bonneville (87-91).Since owning it for a year I am now in the list of happy Bonneville customers.The car was bought for $750 and I put in $950 since owning it.I am amazed on how smooth and effortless the highway drive is.I love the car and would recommend it to all.The 3800 series 1 is on the Wards Top Ten List for best engines this century.It has good pick up and is durable.The sse has ground effects and is cool lookin.Long May the Bonneville Run.

you musta got one of the good ones.

btw, is the offending vehicle throwing any codes?

The offending vehicle has yet to get a calculated mileage and may not be offensive.

The only code i ever get is for an EGR problem, code 32. But i've checked and cleaned every part of the EGR system and everything seems to be in good working order so i don't know what the problem could be. The valve moves freely, the vacuum line is in good condition, and the soleniod works as it should.

This is very true, when I fill up the guage goes well over full. It takes forever to go down to 1/2, but 1/2 to empty is very quick. My bonne does 17-18 MPG all city driving.

My '91 SSE is stock and it has been getting 16mpg (combined) for several years. I can get it up to 20mpg with mostly highway driving and a light foot at the stoplights.

Alec, aren't you the one who has that walker O2 sensor? Maybe that'* the cause for the poor fuel economy? Please eliminate any confusion here, for myself. If the ignition is weak, does the O2 sensor see that as a rich or lean condition? I always thought the O2 sensor saw that as a lean condition, and thus threw more fuel in. But that doesn't make a whole lot of sense.

Also, a gutted airbox doesn't necessarily mean a good flowing induction system. Do you have a new air filter in there?

I believe the PCV Valve can cause poor fuel economy, but I am not 100% sure. Just pull your'* out and shake it. If it rattles, it'* not an issue. The other test, is to pull the oil fill cap, and if it has a vacuum on it [possibly so much you can't even remove the cap] then it is also not functioning properly. If you do get the cap off, it'* possible you could stall the engine due to the major crankcase pressure change.

It could also be a vacuum leak.. or the fact your EGR valve isn't operating properly, or the ECU isn't seeing it'* proper use.

I will also agree with the fellow members, in that you should get your mileage tested via the wonderful testing, minus the fuel gauge. Hit me up on AIM tonight.. I have a few suggestions for you.

Yea i'm the one with the walker O2 sensor. My mileage improved after putting that in. All my plugs are very clean so it'* not running rich (i don't think). It does smell rich out of the exhaust though but that could be the no Cat. thing. I'm not going to buy a new air filter for it until i just go all out and get the CAI so if that'* it well then that'* it. But i am going to start running E85 fuel in it. At $2.89 a gallon as of today, i can't afford regular anymore. Nice thing living in minnesota, we have LOTS of corn to burn. Lol

The alcohol in fuel may be attractive price wise but has less energy content. Interesting to see if the cheaper price will cover for less mileage? Weird that you should mention this since there was just an article in the local paper about ways to get the best mileage. #3 on the list was don't use alcohol blended fuel. Strange to see in a time when we need to stretch the available petroleum, and the alky helps that maybe, but on a personal note, it may cost you more? Alky does suppress knock better.