I also have an '85 300D California version. It has 106,000 mi on the clock. It is in great shape, and gets from 21 to 24 miles to the gallon. The original window sales sticker came with the car and states the expected mileage as 21 in town and 22 on the highway. It dosn't seem to matter much how it is driven. I have taken 400 mile trips and held it at 68 to 70 MPH going and 80 or so on the return trip. There was less than 2 MPG difference, as I recall.