An extra 100 lbs in your vehicle can reduce gas mileage?

Yes, an extra 100 lbs in your vehicle can reduce gas mileage. This is because the engine has to work harder to move the heavier vehicle, which uses more fuel. The amount of fuel used depends on the weight of the vehicle, the speed at which it is traveling, and the type of engine it has. Heavier vehicles use more fuel than lighter vehicles, and vehicles traveling at higher speeds use more fuel than vehicles traveling at lower speeds. Additionally, vehicles with less efficient engines use more fuel than vehicles with more efficient engines.