My Wife'* 99 GP (na 3.8L) has the crapiest gas mileage I've seen from a 3.8L. She'* filling her car with $20 ever 2 days! Where should I start to try and improve her mileage. Car has 100,000 miles on it, no mods, and just regular maint oil changes so far.

same here, my g/fs is a 00 gt. It sux big time. 104,xxx.

Have you guys figured out what the actual mileage is? It might just seem like its crappy, when really their actually driving a lot of miles.

And $20 every 2 days is still only like 6 gallons every 2 days. 100 miles in the city would easily do that.

My GT gets around 19-21 around town and ~28 on the freeway. Thats with 207,700 miles.

But if the cars have 100k on them and haven't had any sort of tune-up, that definately wouldn't be a bad idea. Plugs, wires, 02 sensor would definately be a start.

they get 32mpg on the highway usually if cruise is at 80 and no stopping/passing.


28 is more normal with usual highway driving if you live near a city.

21 in the city or worse. they seem to be within 1mpg of other 3800 cars like bonnevilles and olds/buicks

You should probably calculate the actual fuel mileage she'* getting so you'll have an actual value for gas mileage, not just x amount of dollars every y days. It'* very easy to think you get bad gas mileage when you never actually fill the car up and calculate gas mileage. One of my friends is like that with his 96 Bonneville SE. He'll but $10-$20 of gas at a time, then complains he gets bad gas mileage when he has to fill it again in a few days. He always compares his car to my other friend'* car (a blown LSS) and says, "I used a querter tank going to you house, and his gas gauge didn't even move!" He, however, went fron 1/4 tank to empty, as opposed to having the gauge on full, like my friend with the blown car.

Gas mileage is also heavily dependant on driving style. If she'* the "throttle on - throittle off" lots of throttle-coast-lots of throttle-coast type of person, no car she drives is going to get good gas mileage.

If she drives where she'll accelerate heavily up hills to maintain speed, then break heavily down the hill to maintain speed, she'* going to get bad gas mileage. If she accelerates hard away from stop lights only to stop quickly for the next light, she'll get bad gas mileage.

I don't know if you ever ride in her car when she drives, but you should try it to see how she drives to make sure the problems isn't with her, it'* with the car.

GP GT'* don't seem to get that great of mileage on the freeway since they have 3.29 gears. You can get that kind of mileage at 60, but not at 80. Most members on club gp will tell you that their mileage drops significantly at speeds over ~75mph. From what I've seen, at 80 normal mileage is around 26-28mpg or so.

Id be amazed if my GT got 32mpg at 80.