How to calculate gas cost of trailer?

Answer 1

First, you need to know the fuel economy of your vehicle when not pulling a trailer. You find this out by filling up the tank, then driving a certain number of miles, then filling up again. Then divide (miles driven)/(gallons). For example, say you drove 100 miles, and on the second fillup, you needed to put 5 gallons in. (100 miles)/(5 gallons) = 20 miles per gallon. Call this MPG1.

Next, you need to determine the Miles Per Gallon, while pulling the trailer. You perform the same experiment while pulling the trailer. Suppose you drove 100 miles and then needed 6.25 gallons to fill up. This is 16 miles per gallon. Call this MPGt.

To find the additional gallons needed to travel with the trailer vs. without the trailer, multiply the miles that you will drive by (1/MPGt - 1/MPG1). Then multiply the average price per gallon by the number of additional gallons that you will need, to get the cost for that trip.

So in our example (1/16 - 1/20) = 1/80 (gallons per mile).