These days, cars are getting better gas mileage than ever before. You don’t even have to buy a hybrid anymore to own a vehicle averaging 30 or 40 MPG. Many car owners notice that after a while, their MPG starts to wane. It’s easy to brush this off if you are still getting decent mileage, but this decrease in performance is often a symptom of bigger issues with your vehicle.
These are the most common reasons for a decrease in gas mileage:
Bad Fuel Injectors: Fuel injectors are what puts fuel in your engine. If your fuel injectors are leaking or dirty, less fuel is making it to the engine, leading to a decrease in performance and gas mileage.
Using the A/C Too Often: If you live in a milder climate, consider turning off the A/C and rolling down your windows instead. Having your A/C on wastes a lot of fuel on powering the system. At higher speeds, however, be sure to roll up your windows, as leaving them down creates drag.
Your Driving Habits: If you are an aggressive driver, you may be wasting gas. Accelerating quickly and revving your engine both waste fuel. Idling is also wasteful. Most engines only require 30 seconds or so to warm up, so there is no need to idle your car for several minutes on a brisk morning.
The Type of Oil You Use: The type of oil you choose for your engine can have a significant impact on your fuel economy. If you are using a traditional oil, considering swapping it out for a synthetic or synthetic blend to reduce friction and increase performance.
Bad Spark Plugs: If your spark plugs are misfiring or are otherwise not functioning properly, it can have a negative effect on your MPG. Have your spark plugs checked by your mechanic if you have noticed decreased mileage.
Bad Oxygen Sensors or Air Filters: Having a bad air filter or oxygen sensor can decrease your MPG by up to 20%! Your oxygen sensors help the engine maintain a proper balance of air and fuel, which maintains efficiency. If your air filters are dirty, your engine can’t perform its best. In a way, a dirty air filter prevents your engine from “breathing.”
Tires: Underinflated tires will make a huge dent in your MPG. We recommend you keep an inexpensive tire pressure gauge in your vehicle to periodically check your pressure.