I've been tracking my fuel consumption for the last few months in my new SUV, and I'm consistently getting about 5 MPG less than the advertised epa mpg ratings. I drive a mix of city and highway, but nothing extreme. Is this kind of discrepancy normal, or should I be looking for something wrong with the car?
Five mpg under the EPA rating can be normal for a mix of city and highway. EPA tests run in a lab with controlled temps and no traffic, while your drives include hills, stops, and air conditioning. That gap is common rather than a sign something is wrong.
Start with the easy checks that really move fuel economy. Make sure tires are inflated to the recommended pressure, remove roof racks if you have them, and avoid carrying extra weight. Also confirm you are using the manufacturer recommended fuel and that basic maintenance is up to date.
Weather and temperature have big effects. Cold starts fatten the bill and heating or cooling the cabin adds load. If you mostly drive short trips or keep the AC on a lot, mpg can stay lower.
Keep a simple log for a few tankfuls noting miles driven gallons used outside temperature and whether the AC was on. Look for patterns and see if the gap shrinks on longer highway runs.
Remember that the EPA rating is a target not a promise. If your car has different tires wheels or drivetrain or if you drive with a heavy foot the real world mpg may be lower.
If you want to get serious you can compare a few tankfuls before and after a maintenance task like replacing a air filter or fixing a misfire. But be careful not to chase tiny swings.
If you want I can help you calculate a rough expected range based on your model and your average trip length. What make and year is your SUV and what is your typical driving mix?