Originally Posted by KatanaPilot
Similar RV pulling the same Toad and about the same mileage. I'm not unhappy about it at all. It's a 11,000 pound vehicle with the aerodynamics of a barn door (perpendicular to the wind) pulling a 2500 pound car. Anyone expecting 16-20 mpg with these things is overly optimistic.
My step-brother is an engineer in the R&D department for GMC and works at the Milford proving grounds most of the time. With diesels, research has shown that you will get your best fuel mileage by keeping the engine RPM's within the engines "Torque" range. If your RPM's are below the torque range the engine will struggle and you will waste fuel., if the engine RPM's is above the torque range, you will be producing horsepower instead of torque and horsepower requires energy, i.e. FUEL
The torque range for the V-6 24 valve Turbocharged clean diesel engine is 1400 RPM - 2400 RPM. Cruising in fifth gear with the engine turning 2400 RPM equates to 60 MPH on a flat road with no headwind. Anything faster that 60 MPH equates to getting less fuel mileage.