* Aerodynamics: Heavier vehicles are generally less aerodynamic than lighter vehicles. This is because they have a larger frontal area and a higher coefficient of drag. As a result, heavier vehicles experience more air resistance, which decreases fuel efficiency.
* Rolling resistance: Heavier vehicles also have more rolling resistance than lighter vehicles. This is because the tires of heavier vehicles must work harder to support the weight of the vehicle. The increased rolling resistance results in more energy being lost to heat, which reduces fuel efficiency.
* Engine efficiency: The engines of heavier vehicles must work harder to move the vehicle. This is because they must overcome the increased aerodynamic drag and rolling resistance. The harder the engine works, the less efficient it becomes, which results in decreased fuel efficiency.
Of course, there are some exceptions to this general rule. For example, some lightweight vehicles may have very efficient engines that offset the disadvantages of their low weight. Similarly, some heavier vehicles may have aerodynamic designs that help to reduce drag. However, overall, the trend is for MPG to decrease as vehicle weight increases.
Here is a table showing the average MPG of different vehicle types, based on data from the US Environmental Protection Agency (EPA):
| Vehicle Type | Average MPG |
|---|---|
| Subcompact car | 33 MPG |
| Compact car | 30 MPG |
| Midsize car | 27 MPG |
| Large car | 25 MPG |
| SUV | 20 MPG |
| Pickup truck | 17 MPG |
As you can see, the average MPG of vehicles decreases as the vehicle type gets heavier. This is consistent with the general trend of MPG decreasing as vehicle weight increases.
