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If you can, pick one pump at one gas station. Fill there for 2-3 tanks using the same method, ie, stopping at 1 click or 2 clicks. That will give you a good idea of your fuel mileage.

Filling from half a tank from various gas stations is about the worst way to calculate fuel mileage. Between the different pumps and the different driving techniques used, calculated mileage will vary a lot.

Get the car up to 30 mph quickly, then keep it moving.

Why not just let the DIC in the car tell you? Don't all of these cars have an Avg MPG display?

Ken_W

Not before 2000.

Plus, the Avg. Mileage in the DIC isn't terribly accurate. Like, .5-2 MPG off, generally on the high side.


And SE (base) Bonnevilles don't have DIC's in any year.

00Beast wrote:I got 24 MPG going from St. Cloud to St. Peter MN on mostly 2-lane backroads this afternoon (If I had originally known I'd be going to St. Peter, I'd have taken freeway, but didn't know till halfway home) which was really good considering the amount of passing and slowing and accelerating I did. I set the cruise at about 63 and let it roll.

Eh, that's pretty poor for that trip and your car!

Stop racing everyone you see ed

BonneMe wrote:

00Beast wrote:I got 24 MPG going from St. Cloud to St. Peter MN on mostly 2-lane backroads this afternoon (If I had originally known I'd be going to St. Peter, I'd have taken freeway, but didn't know till halfway home) which was really good considering the amount of passing and slowing and accelerating I did. I set the cruise at about 63 and let it roll.

Eh, that's pretty poor for that trip and your car!

Stop racing everyone you see ed

Honestly, that was a couple of passes @ ~60% throttle, but mostly cruising @ 63. The problem is getting behind ppl going 52 and having to slow down and stop in all the small towns on the way. If it was all freeway, yeah I'd have done better.

My 97 SE got as good as 35mpg highway and 26-27 average. With 114,000 miles
The 02 SE has gotten 28 highway and 22-23 in town. With 83,000 miles
Granted as long as I don't try and go like a bat of of hell light to light or break the speed of sound on the highway.
Using regular 87 octane gas in both with gutted air boxes and K&N air filters.

i only get a little over 200 miles per full tank of gas ouch... new plugs wires MAF, IAT..... newer tires 160k on the clock

SLEking wrote:i only get a little over 200 miles per full tank of gas ouch... new plugs wires MAF, IAT..... newer tires 160k on the clock

you do realize thats 11mpg, right?

Sounds like you need to finish your tune up, that is downright horrible. I get better mileage in my truck, pulling a car.

I just calculated my mileage on my '95 Bonneville the other day and I got about 27mpg, having gone about 325 miles on 3/4 of a tank of gas. About 2/3 of that was interstate highway miles and the rest was city driving.

Now here's the kicker--all but the last 20 miles or so was driven before I changed the spark plugs and wires on Sunday. The car was was running terribly for most of that weekend trip. I discovered when I changed the plugs and wires that the wire to the no. 5 cylinder wasn't even firmly connected to the plug! The car is running silky smooth now and I'll be interested to see how that little tune-up affects the mileage.

When we took our trip to Myrtle Beach...

All the way there, and back, going thru the mountains, was a good 28-29MPG.


City..... I'm going to make a good guess at about 20.

Ok SLEking, what have you replaced? Full list, brands and how many miles ago.

i just put a new ICM on, new MAF, Bosch wires (lifetime warranty), ac delco plugs (the expensive ones 7.00 a piece) new oil filter all less than 500 miles ago

How old is your O2 sensor? That would be the next thing I'd look at, and replace. I'd recommend an Ac Delco, but Denso or NTK will work too.

thanks beast. ill look into it. btw 02 is stock.

If you don't know, it's on the rear manifold, and the best way to access it is from the top. You will want the special socket that your parts store sells, and a shot of penetrating lube and a big bar may be necessary to replace it. Mine took a u-joint, a couple extensions and a cheater pipe to finally pop loose. Apply anti-sieze to the threads of the new one and put it in.

"Cheater pipe" = breaker bar?

Ken_W

Due to the heating of the manifold they can get become hard to get out.
So you put a longer pipe on the end of the breaker bar to add leverage.

A 19mm open-end wrench will do in a pinch.

I'd recommend Delco for the O2 sensor. There are some differences, like the sheath and wiring, that indicate higher quality than a Denso. I posted about this somewhere.

If you do the 02 sensor while the rear manifold is warm, itll help a lil bit to get it loose.