What Factors Affect Your Car’s MPG Rating?
When you look at the mpg – miles per gallon – rating for a car, you may wonder if you’ll actually be able to get that number when you drive the car. That depends on a number of different factors, but there are several steps you can take to maximize your car’s mpg.
You may have heard that jackrabbit starts – more formally known as quick acceleration – and quick stopping can reduce your mpg. What you may not know is that you can lose up to 33 percent of your mpg with this kind of driving. So forget the jackrabbit – slow and steady really does win the race, especially when it comes to increasing your car’s gas mileage.
And although most cars are designed for aerodynamics, exceeding normal highway speeds can reduce your fuel economy. Other things that interfere with your car’s aerodynamics – like cargo racks, for example – can also reduce your fuel efficiency.
While towing a trailer also affects the aerodynamics of your car, it’s the extra weight that really decreases your fuel economy. EPA testing assumes only 300 pounds of passengers and cargo, and two healthy adults could exceed that amount on their own. If you plan on hauling your boat or camper this summer, plan to pay a little extra for gas.
In addition, to operate efficiently, your engine needs to be broken in. On new cars, this can take anywhere from 3,000 to 5,000 miles. Your car engine should also be operating at optimal temperature. This means that driving in cold weather or making short trips, can reduce your fuel economy because your engine doesn’t reach this temperature. The EPA says letting your car idle to warm up doesn’t really help – it actually burns more gas to let the car idle than you can save by letting the engine warm up.
Speaking of temperature, the car’s internal temperature can make a difference in your gas mileage too if you’re running the air conditioner. Running the air conditioner on its maximum setting, for example, can reduce your mpg up to 25 percent. Other electrical accessories can reduce fuel economy as well.
Also, EPA mileage tests assume you’re driving on level ground, so if you’re doing a lot of traveling on mountainous, hilly terrain or on rough, unpaved roads, expect your mpg to be a little less. The same goes for 4-wheeling – using all 4 wheels means the engine works harder and burns more fuel. Optional 4-wheel drive models are always tested in 2-wheel drive mode to improve the mpg ratings.
The other things that can make a difference in your fuel economy are the things you’ve been hearing for some time. Keep your engine properly tuned, keep your tires properly inflated and aligned, and keep your air filter clean – especially if you have an older car with a carburetor.
Know also that gas can vary. In summer, gas provides more energy than in the winter, and oxygenated fuels or RFGs (reformulated gasoline) can reduce fuel economy.
Of course, some of the things that affect your car’s mpg are beyond your control, like the state of the roads on which you have to drive. Other things you can do involve your own personal driving habits, like avoiding jackrabbit starts and keeping your car well maintained.
