Well, these things will still beat the Army's M-88 Tank Recovery Vehicle. Basically a tow truck for tanks. GAS powered, not diesel, and 12 cylinders. 1200 cubic inches, IIRC, with spark provided by 4 magnetos. Gas mileage? Well, no, youi can't really call it that.
5 gallons to the mile.
No, NOT 5 miles to the gallon. 5 gallons to the mile.
8 when towing.
But you WILL get the right of way on the freeway!