Towing a vehicle and gas mileage

Ah yes, the devil is in the details. Renting a 14-foot truck and yes, the car dolly means only the rear wheels are on the ground. The car is an AWD Subaru and from the other posts, it sounds like it is not a good idea to tow this particular vehicle on a car dolly. Good question about the truck’s engine and gas/diesel. I’ll do more research.