I occasionally see these in my price range. I found these outrageous claims on the web last week. My current truck gets 9mpg towing.
"Our Jeep has the heavy duty trailer towing package. I pulled a 16’ car hauler trailer and Alfa Romeo from San Jose to Washington State and got 20 mpg. That’s a 1,000-mile journey. The only change that would have made the trip more pleasant would have been the addition of an equalizer hitch. I didn’t know about such things at the time. "