MPG Reality Check

[Dorn Hetzel]

I get between 9 and 10 mpg with my 77FC35, but we don't tow anything.  That was measured over a 5000 mile round trip to AZ from GA with side trips last year.  Our average speed (by GPS) was around 62.  Top speed around 72 on flat stretches with a tail wind

So 6-ish towing something doesn't sound completely unreasonable.

Dorn Hetzel

77FC35

Hogansville, GA

On Fri, Feb 12, 2010 at 3:17 PM, freewill2008 <"sundance101@comcast.net"> wrote:

 

Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles, and filled it again. The 167 gallons calculates to about 6 MPG.



The method has plenty of potential for error. The odometer reads low and I don't have a GPS. I used the Google mileage plus 5% to account for wrong turns, finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and Malibu, CA.



The tank is so big that I figure the fill could be off by as much as 10%. If the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10% high, the MPG would have been about 5.5.



Other details: 1984 FC31 with California 210HP turbo 3208. Road speed about 58 MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda CRV. Air filter has about 5000 miles. The air intake is the enlarged version designed for the 250HP turbo engine. Never blows any black unless I make an operator error.



To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate would need to be off by almost 700 miles, or the fill-up would need to be off by almost 70 gallons.



I'd be interested any anyone else's MPG observations and the method used.



Bob Griesel '84 FC31 WLII WA