I would say a lot. Anything that adds a significant amount of weight to your car will always affect the gas milage.
The best way to see just how much it affects would be to use a full tank of gas without the trailer (keep track of how many miles you drove) and then use a full tank of gas with the trailer (keep track of how many miles you drove). Then compare how many miles you went on each tank of gas. :happy:
Yes it does affect the gas milage. That is why when you mail something it is based off of weight. The more something weighs, the more they charge for it because it uses up more gas for the transportation of mail.
Well, that makes sense, Crissy. I hadn't thought of it that way. Carl - good idea, but not sure I'll get around to actually executing it! LOL! I don't really use the trailer that much.
Anytime there is a load on a vehicle it will affect gas mileage. The heavier the load being towed, the more of a difference it makes. Wind and terrain will have an effect too.