For a certain city, the table shows the average fuel efficiency in miles per gallon (mpg) for different types of vehicles. Based on the table, how much greater was the average fuel efficiency of a compact car than a pickup truck?
| Type of Vehicle | Average Fuel Efficiency (mpg) |
|---|---|
| Compact Car | 38 |
| SUV | 25 |
| Pickup Truck | 18 |