Before going out to buy that toy hauler, you want to know how your SUV gas mileage is going to be affected, and how to minimize any adverse affects to your SUV fuel economy.
The Towing Capabilities-Fuel Economy Relationship
The short answer is that as towing capabilities increase, SUV gas mileage decreases. The amount of torque an engine produces will be the single biggest determining factor in towing capabilities. Higher towing capacities require increased engine output. Engine output is directly related to how much air and fuel the engine consumes to go through a single revolution. One way to increase engine torque output is to increase the size of the cylinders. Increasing the size of the cylinders increases the displacement of the engine. The displacement of the engine can be described simply as how much air and fuel can fit in the cylinders during the intake cycle. So, if an engine is rated as a five liter engine, this means that five liters of air and fuel are consumed by the engine for every rotational cycle, uncompressed. However, this air fuel mixture isn’t half air and half fuel like many people believe. The actual ratio of air to fuel is calculated stoichiometrically. A stoichiometric equation or reaction, such as what occurs in the combustion chamber of an engine is one where both reagents are completely consumed by the reaction, in this case combustion. In the perfectly balanced engine, this is 14.7 parts of air to one part of fuel. So, in the aforementioned five liter engine, each rotational cycle of the engine consumes approximately 4.66 liters of air for every third of a liter of fuel. Unbalancing this equation and adding more fuel is one way to increase the power output of an engine. Thus, increasing the towing capabilities of the vehicle. When this is done, SUV gas mileage starts to drop as more power is made by the engine.
The above information was given to help you better understand the inverse relationship between towing capabilities and SUV gas mileage.