I have a 95 D1 3.9 (85000 miles) that gets around 10-12 mpg. I was just wondering what is a normal mileage rating for the 3.9.

 

You would have to give more info. Is it stock? what type of tires are you running? Any add ons (bumpers, rack, etc)? I believe most here are getting 14-15 city and 18 or so hwy. I would go through mikes 60k service list found at the top of the page and once it is in tune, check your milage again.

 

With a good tune up and premium gas and a light foot on the throttle you can expect 12-14 city and 16-18 expressway.
The trick on the expressway is to keep it at 65mph or less.
As a daily driver I get high 14's and low 15's every single week when I get gas.

 

On my 144K '00 D2, I got 12.96MPG on the very first full tank of gas, after buying it from a Little Car Lot; no work done on the engine yet.

 

To increase your in city gas mileage average, drive in 3rd gear. I average about 13.5-14.5 driving mostly on 35-45 mph roads with rolling hills. The only time I put it in "D" is on the highway where I get 18-20 MPH.

I drive with 8 mm magnacores, plus 4 plugs on stock 16 in. tires (40 psi all the way around) w/56K miles on the motor and only use premium gas (92). Sometimes I even put it in "2nd" gear on some hills I drive to keep the RPMs around 2K. Always a light foot on the gas.

Spike and Mike can go more into details as to why to run a lower gear in certain situations. But in my experience, I get better gas mileage around 2-2.5K RPMs vs. 1-1.5K RPMs.