I'm kinda pissed off right now. I just filled the tank today. I was doing some milage calculations. I filled with 11.7 gallons of 92 octane. My gauge was right at the first notch before the "E". Then it hit the "E" once again today. I had 185 miles. Doing the math, I got 15.8 mpg averaged. That is not good. I even drove light on the pedal to test it all out. I started the car about 5 times in the morning during this fill for about 10 minutes each. Even though I warmed up the car, I don't think the milage should be that low.

Doesn't have anything to do with the winter weather. How'* power? Got plenty?

If power is good, and ONLY mileage sucks, change the O2 sensor.
Part numbers and prices up in Techinfo/specs


If your power seems to be lagging, too, do the whole deal. Plugs, wires, fuel filter, O2, PCV, air filter, etc.

I'm getting the same mileage with mine.
Always have since new and it'* only got 10 K mi now.
Great power.
Do you still recommend changing the O2 sensor?
I do notice that it spits black carbon soot out the tailpipe when it'* cold.

The cold could have everthing to do with the poor mileage.

How long have you been driving? Are you a new driver? If not, I would be surprised if you have not noticed a sharp reduction (% wise) in winter mileage before with other vehicles you have driven, especially large vehicles like the Bonne (if you have owned other large vehicles).

Cold weather can hack the crap out of mileage although that seems a little low.

1. Tire pressure is probably down.
2. Oil, especially if a little old, will circulate like molasses.
3. Grease in bearings will be like, well....frozen grease.
4. One of the biggies is the thermostat? The colder it is the longer it will take to open thereby preventing your overdrive from kicking in. Ever notice that you have no OD until she gets nice and warm.
5.Cold fuel does not atomize as well as warm fuel.
6. Differential fluid will flow likeileage although that seems a little low.

1. Tire pressure is probably down.
2. Oil, especially if a little old, will circulate like molasses.
3. Grease in bearings will be like, well....frozen grease.
4. One of the biggies is the thermostat? The colder it is the longer it will take to open thereby preventing your overdrive from kicking in. Ever notice that you have no OD until she gets nice and warm.
5.Cold fuel does not atomize as well as warm fuel.
6. Differential fluid will flow like molasses.
7. Rear end lube will be like mud.
8. Yes, and even a cold coil pack can reduce combusion as well.
9. Remember the thick crap in the power steering pump.
10. Don't forget even the idler pulley bearing grease.

All of the aforementioned, and many other factors, can drop your mpg by a factor of 30% or so depending on how cold it is, ice and snow on the roads, more stop and go traffic ahead of you etc., etc., etc. Think about it. A 1/8 hp reduction here; a 5-10 hp reducti molasses.
7. Rear end lube will be like mud.
8. Yes, and even a cold coil pack can reduce combusion as well.
9. Remember the thick crap in the power steering pump.
10. Don't forget even the idler pulley bearing grease.

All of the aforementioned, and many other factors, can drop your mpg by a factor of 30% or so depending on how cold it is, ice and snow on the roads, more stop and go traffic ahead of you etc., etc., etc. Think about it. A 1/8 hp reduction here; a 5-10 hp reduction there.........and viola! Mileage and power down the tube, especially during the first 10-15 minutes or so anyway.

Get her nice and warmed up. Then go top the tank up and check your mileage after a big easy run down the I-state at steady state. You will probably find you are back in the mid to high 20'*. If you still are not, you can bet that something went south since cold weather set it (and that would not be you!). Hey, how is that thermostat anyway? Remember the OD.

We also have to compare apples to apples. Sol has an SSE. Can't compare to an SSEi in the mileage department.

I'm not about to change my O2 sensor.
I think the poor mileage I'm getting is normal for the short city trips around here.
The normal driving time from when the engine is dead cold is never greater than 10 min.
It hardly ever gets a chance to warm up. So I don't expect good mileage in town.
When I go on longer highway drives the mileage is much better.

I am not a new driver, and I have drove in winters before with this car, but never kept track of the milage then.

I have enough power. It still feels like it always does. I know that the O2 has never been changed as long as I had the car, but I don't wanna jump to conclusions right away. I'll keep track of everything else. I hope it is just the cold. I am a daily driver with this, and you all know about weather here in Michigan.

Sol, if you have 50-60k miles on that O2, it'* due. I'd be willing to bet you at LEAST 2mpg for changing it. It has to be at least part of your problem if it'* that high.

OK.

What brand do you use? and how much $$$ ?

Jr, me, and Terminator (I think) have all had problems with Bosch. Somebody else had trouble with some other brand. Jr and I will tell you absolutely....buy AC Delco ONLY. I posted all the part numbers and prices up in Techinfo, Specifications.