[GH85Carrera]

My 1985 911 has a 21 gallon gas tank. I have driven over 500 miles on one tank a few times. Usually when heading back home. I try to fill up with whatever gas I can get, and be near empty when I get home to get a tank of gas locally. If I am coming back through Arkansas, they sell 100% gas with no alcohol so I get the best mileage. Coming from Colorado, it is downhill all the way, and that helps as well. 5,000 feet to 1,200 feet.

I am not risking running out of gas, so I figure 19.5 gallons of gas with a comfortable reserve is 25.6 MPG will get me there. I do have a taller 5th gear than stock, and 255/45/17 rear tires.

I don't off hand remember the numbers for the 5th gear, but I have a post in on the tech site about it.

I drove my old 1974 914 2.0 non stop from Houston, TX to my grandmother's house and that is 500 miles. It was in the bad old days of 55 MPH national speed limit no speed records.