I have a 1993 850 GLT which has given me minimal problems despite my aggressive driving style. Lately though I have brought my car from Syracuse NY down to my school Philadelphia, since the trip I have been experiencing dreadful gas mileage. I have eased up my driving style, taken the car out of sport mode and into econ yet I am still experiencing about 10.5 MPG. The car has only got 80,000 miles on it does any one have any ideas of what could be wrong with my car?

You may have a problem with your fuel pressure regulator. Do a search in these forums, I don't remember if the problem is when the diaphragm ruptures and allow gas into the vacuum lines, or excess fuel pressure dumping extra fuel into the injectors. I think someone suggested using clear line for the vacuum side to visibly check for signs of raw fuel.

My experience is that sport and economy aren't significantly different gas mileage wise. When was your last tune-up? Air filter, oxygen sensors can be checked. Any engine codes?

Sorry--I have no idea, but I do have a question: What is "sport mode"? I have a 1993 850 GLT as well--manual transmission. Is the sport mode a feature for automatics? What does it do?

Thanks and good luck. Let us know the resolution.

98,000 K

Yes, "Sport Mode" is a feature of the automatic transmission. When switched to "Sport Mode" from "Economy Mode", the transmission behaves differently by switching gears at higher RPMs, similar to what you would do in a manual transmission for maximum torque. Also, the kick down repsonse from your throttle is more sensitive. The same switch also has a "Winter Mode" which has the transmission starting out in 3rd gear to prevent spinning of the tires on ice or any other slippery surface. I have never used the "winter mode".

The dreadfull gas milage is probably due to either a clogged up gasoline filter or a PCV filter. BTW... The winter mode works very well in ice in conjunction with the traction control. Best of luck.

95- 850 T-5R 67,000 miles
82- 240 GLT (Now defunct)

Believe it or not, since the change in weather I have noticed about 2-3 MPG less. I have been told that it is the addatives that are put in the fuel for the low temp. That of coarse doesnt explain the 10+ MPG degradation that was posted. Just some of the problem.

(I live in South Central PA)

I've always been skeptical of minor mileage variations, but here are some possible explanations:

--During warm weather, your car warms up quickly and burns a leaner mixture a greater percent of it's running time, than in -10 weather.

--During -10 weather, air is denser, requiring more fuel to reach a proper mixture.

--During -10 weather, you go out and start the car and let it idle for 15 minutes before driving-off in the morning.

--During -10 weather, when you go to fill up your car, and the nozzle clicks off, it's too cold to stand out there and add a little bit more. During warm weather, maybe you add 'till the second, or third click, but not at -10.

--The thicker oil in your engine, transmission and differential increases the internal resistance of you drivetrain.

--Your tires have less traction going through snow and ice, so for every 20 rotations of your tire during the summer, you are doing 21 rotations at -10.

--Your car is heavier and less aerodynamic with all that snow, salt and ice on it.

--You front brake calipers are probably dragging a little more than in warm weather 'cause they rely on the flxibility of the caliper piston seal to retract the piston when you let off the brakes. And at -10, that flexibility is attentuated.

I think you add all these things up and you get 2, or 3, less miles per gallon.