bclan6
we have taken two trips to FL from western NY in the last two years. The first year with no dolly and car, and held the speed to 55-60 mph. This year we had the dolly with a car and two extra people and a baby with us. We also did closer to the speed limit the whole trip. We saw a difference of less than 1 mile per gallon with the dolly and car.
Also found having the car made things more enjoyable. Yes we had to skip a few gas stations and some store parking lots, due to not being able to back up.
Unit is on a Ford Gas chassis and is 34 foot long plus dolly and car. Weight with dolly and car approximately 21,000 lbs. Have fun and enjoy.