Check your odometer against a GPS or measured mile. Not the "Speedo" as you listed above. Use a GPS that shows the distance you have traveled in 10ths of a mile. Your speedometer error is one thing the odometer is another. Mine is actually about the same as yours with the Speedo. But the odo is 20% off!

I have found that if I follow my odometer and use that figure against what I put in at the pump. My mileage is only 21.3.

After using a GPS and having the odometer apart now I know that my odometer is exactly 20% off. This puts my mileage right at 26 to 27 MPG. I have been checking it ever since I bought the car and it always the same. Usually 26.3 sometimes a little more.

I don't believe 30 MPG with an automatic. Unless you are up in the mountains. Even then I have a hard time believing that. Maybe with a car modified with a stick.

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AJ

1985 300D (SOLD)