1997 850 Wagon NA Still getting crappy MPG

[dairyqueen814]

@DairyQueen: Great info, that's about 16.5% better. Like saving 54 cents per gallon.

I'm sure it's even better than that because that was half a tank on the bad thermostat! The mpg that I got with the new thermostat is probably about 26-28! That's around almost 40% better. I'm pretty excited.

[dairyqueen814]

@ Jacob: Huh? What difference would parking in a direction make when fueling? A gallon is a gallon no matter where the car is parked. Driving habits can make a big difference, 15% easy.

Also I've noticed that when my car is facing downhill my gas gauge reads about 1 more gallon and when I'm facing up hill its about 1 gallon less. Never really thought twice about it though.

[rspi]

If for some reason you don't have a trip/mpg gauge in your car you should calculate your mileage based on miles and gallons used not an estimate of gallons used. Either you pumped 12 gallons or 11.

I believe everyone should have some kind of computerized mpg estimator.

One thing that does surprise me is that my mileage does drop that much when my car is full of crap. Maybe being turbo has something to do with it.

[rspi]

The mpg that I got with the new thermostat is probably about 26-28! That's around almost 40% better. I'm pretty excited.

That is awesome!

[dairyqueen814]

If for some reason you don't have a trip/mpg gauge in your car you should calculate your mileage based on miles and gallons used not an estimate of gallons used. Either you pumped 12 gallons or 11.

I believe everyone should have some kind of computerized mpg estimator.

One thing that does surprise me is that my mileage does drop that much when my car is full of crap. Maybe being turbo has something to do with it.

Oh no I always go by what the pump and my odometer say
I'm just commenting on the fact that when I park my car facing up hill and come back the gas gauge is lower than when I left and when I face down hill and come back it's higher than when I left. I'm too neurotic to calculate anything based on estimations

[jacobharding]

I am assuming, but I don't have proof, that depending on the angle of the vehicle and where the filler neck enters the tank that it is possible, but not certain, that an air pocket could become trapped on the tank therefore causing fuel to travel up the filler neck without the tank being totally full.

The method by which I have always checked my MPG is:
1: Fill the tank (first click, top it off till gas shoots out, whatever...just be consistent).
2: Reset trip odometer or record current odometer reading.
3: drive, drive, drive. The closer to empty you get the more well rounded your result will be.
4: Refill. Replay your step 1 scenario as closely as possible.
5: Divide miles traveled by gallons that went back in on second fill-up.

I have been told to make sure to fill-up in the same temperature as well but that is a myth. Yes, the temperature of liquid changes it's volume but here in Virginia the freeze line is about 18". Below this and the ground stays a pretty consistent temperature year round. I am certain that those big fuel tanks at the station are well below that so really it doesn't matter if it is -10 below out, or a sweltering 100 degrees, the gas coming out of the nozzle should always be of about the same temperature and density.

[jacobharding]

That's odd jacobharding, I found exactly the same thing trying to improve my mileage. ECO vs SPORT, driving like I had an egg between my foot and the loud pedal, keeping speed below or at 60 MPH. Yeah, a little difference but overall, nothing significant. The only real killer for me was bumper-to-bumper Boston traffic and even then 18~20 MPG most of the time. I lead-foot now, 100 miles a day, 24.4 MPG on mid-grade gas in a 98 LPT w AWD (disconnected).

Yeah, I was going to say something about getting worse mileage in the winter because I have a bad habit of starting my car 15 min before I leave because I HATE being cold. Idling (including bumper to bumper driving) equals 0mpg and will throw your averages WAY off.

[faster4tec]

You first mentioned your idle was 950./1000rpm, that sounds very high to me.

[dairyqueen814]

You first mentioned your idle was 950./1000rpm, that sounds very high to me.

I thought it was supposed to be between 750 and 800 but no one has said anything about it so i assumed it was fine
any suggestions?

[rspi]

Book idle is 840 rpm.