Tom/Barb wrote:
I believe it's all about weight to horse power ratio.
your V10 gas is working harder than my 8.3 diesel.
we usually run light, coach empty weight is 27k, we usually load under 1000#, we don't tow heavy the jeep is only 4288# that brings us across the scales at a little over 32k.
Holding tanks, plus fuel will vary
A bigger difference than the power to weight ratio for fuel economy is the gas vs. diesel engine. Diesel is about 15% more dense than gasoline and, not at all coincidentally, has about 15% more energy per unit volume than gasoline. Weight has relatively little impact on fuel usage when cruising on a flat road, as it doesn't greatly affect the overall friction of the vehicle which is mostly air resistance at highway speeds. (Weight has a significantly higher impact when going up hills or in stop-and-go driving, of course).