Just for comparison sake only! My 2004 2500 quad cab 4wd with a 5.9 Cummins, 6 speed stick, 3.73 gears gets 17 mpg towing my 18’ open car trailer with a car on it. Got 14 mpg towing a 12k dry weight 5th wheel. Gets 23-24 mpg empty. All of those are keeping the rpm’s right at 2000, which puts me at 70 mph. Plenty fast enough while towing.
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