Aside from the entirely new set of driving skills you have hopefully mastered while towing your trailer, you have to learn proficiency in the logistics of tongue weight, gross trailer weight and hitch strength. And then there’s the detriment to the gas mileage you’re used to…
Decreased gas mileage when towing is an unavoidable reality. The heavier the load, the more force you need to tow it, which is of course provided by your engine. The more force your engine must produce, the more gas it’s going to consume (force equals mass times acceleration).
Whatever mileage your car is rated to get, you can be certain you’ll see that mileage drop in direct proportion to how much weight you’re pulling. This is because when car manufacturers devise the weight rating, they’re assuming the car will only carry 300 pounds of cargo, including passengers.
But there are ways to get the best gas mileage when towing. There are a number of things that impact your gas mileage when towing. In addition to the weight of your load and how bulky it is, factors like how fast you drive and whether you’re using a gasoline or diesel engine will play a role.
For example, while diesel fuel is usually more expensive than gasoline, diesel engines can get 12 to 15 percent more power out of a gallon of fuel, so depending on how much you tow, the trade-off could be worth it. In addition, diesels tend to have more pulling power than gasoline engines, enabling them to tow heavier loads without working as hard.
Larger, more powerful engines don’t see as much of a drop in gas mileage when towing as smaller ones do. They simply don’t have to work as hard because they’re designed for that extra load. So even though large vehicles never get excellent mileage, when compared to small or medium-sized vehicles that may only get 60 percent of their rated fuel economy when towing, these larger engines may actually come out on top.