I’m on my first road trip with my 2000 Scamp 13 being towed by a 2011 Ford Ranger with a 4 Liter, 6 cyl engine and a manual transmission (factor).  I’ve been pleasantly surprised that my gas mileage has dropped as little as it has, and my travels thus far have required a fair amount of steep climbs requiring second gear and in one case first. I know some folks behind me probably weren’t “happy campers” but what else is new in today’s fast paced world. I upgraded a year ago to a true truck tire which unhappily reduced my gas mileage more than I liked; from an average of ~22 to ~19.  Of course winter, short trips, and hauling a utility trailer reduces it even more. So far on this trip, my mileage seems to be running about 18.5+ mpg which has pleasantly surprised me.  A couple of plausible reasons/recommendations. Tire pressure: keep tow vehicles tires near upper range limit. If the ride is too rough, you can try to reduce the tire pressure slightly in both front tires by the same amount to reduce jolt. Make sure Scamp tires are up to max recommended pressure to reduce towing resistance. Leveling: make sure your hitch is such that the trailer and vehicle ride level. Before I left, I had an air lift kit installed primarily because I found that just a moderate amount of tongue weight would drop my hitch almost 2 inches guaranteeing that my trailer and vehicle wouldn’t be level and I’d have oncoming drivers flashing their headlights in my eyes thinking my high beams were on. Road miles and speed: I think the final contributing factor is that I’m putting on highway or road miles as opposed to short trips and constant start/stop although driving back and secondary roads have produced enough of the latter. And because my “MO” for this trip is secondary road travel to slow the pace and relax, my speed is typically more in the vicinity of 45 - 50 than it is 60-75.   All of the factors mentioned are influential in affecting mileage while towing.