The most straightforward way to check your car's MPG (Miles Per Gallon) is by using the vehicle's onboard trip computer. This system calculates your real-time and average fuel economy based on data from the engine's sensors. For those who want the most accurate measurement, the manual calculation method—tracking miles driven and gallons used over a full tank—is considered the gold standard.
How to Use Your Car's Onboard Computer
Most cars manufactured in the last 15-20 years have a trip computer. You can cycle through the display options on your instrument cluster or infotainment screen using buttons on your steering wheel or dashboard. Look for menus labeled "Fuel Economy," "Average MPG," or a similar icon. You can usually view:
- Instant MPG: A real-time reading that fluctuates heavily with acceleration.
- Average MPG: A more useful figure representing your fuel efficiency since the last reset.
- Distance to Empty (DTE): An estimate of how many miles you can drive before refueling.
Resetting the average MPG counter after refueling gives you the most relevant data for your current driving cycle.
The Manual Calculation Method for Ultimate Accuracy
While convenient, the car's computer can be slightly optimistic. For a precise measurement:
- Fill your gas tank completely until the pump automatically shuts off.
- Reset your trip odometer to zero.
- Drive as you normally would until the tank is at least half-empty.
- Refill the tank completely, again noting the number of gallons it takes.
- Divide the miles driven (from the trip odometer) by the gallons used to refill the tank.
For example: 320 miles driven ÷ 12.5 gallons = 25.6 MPG.
Factors That Influence Your MPG
Your displayed MPG will vary based on driving habits, traffic conditions, vehicle load, and even tire pressure. Aggressive acceleration and high-speed highway driving typically lower your fuel economy. The following table shows the EPA-estimated MPG for a range of common vehicle types, which serves as a useful benchmark for comparison.
| Vehicle Type | Example Model | City MPG (EPA) | Highway MPG (EPA) | Combined MPG (EPA) |
|---|
| Compact Car | Honda Civic | 33 | 42 | 36 |
| Midsize SUV | Toyota RAV4 | 27 | 35 | 30 |
| Full-Size Pickup | Ford F-150 | 20 | 26 | 22 |
| Hybrid Sedan | Toyota Camry Hybrid | 51 | 53 | 52 |
| Electric Vehicle (MPGe) | Tesla Model 3 | 132 MPGe | 134 MPGe | 133 MPGe |
