Real world fuel economy comparison

422 SS · October 18, 2003

I finally had a chance to do a real world comparison between a 8.1 and a Duramax while towing.My local car club rents Norwalk raceway in northern Ohio a couple times a year and I used the Dmax to tow this time (no longer own the 8.1).I have a 28ft enclosed car hauler that has a 6 inch taller roof than a regular one.Needless to say it makes for serious wind drag at freeway speeds.

Last year 8.1 gross weight 15,800 lbs avg fuel mileage 6.8mpg

This year Duramax gross weight 16,400lbs avg fuel mileage 11.85 mpg

Average speed was between 60-75 mpg depending on what traffic would let me do.

This was a 280 mile round trip 40% on two lanes.The hills on I-71 that the 8.1 pulled at the rev-limiter in 3rd were tackled by the max in OD at 2000 rpm.The Dmax made it on 1 tank of fuel with over a 1/4 tank left (longbed).The 8.1 required a fuel stop on the way back(shortbed).That comes out to a nearly $30.00 fuel savings on this relatively short trip(current prices).That is half of what the Dmax added to my monthly payment.These are real #s from as close to identical comparison as I can come up with.