BUYER’S GUIDE: Understanding Fuel Economy Ratings

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Gas LabelHow high on your list of priorities is fuel economy?

Fuel economy determines how much gas you’re going to use. Not figuring this into your budget can be problematic when gas prices rise. Remember when gas prices jumped and everyone rushed to trade their big SUVs for smaller, fuel-efficient cars? Buy a fuel efficient car at the start and you won’t have to worry as much when gas prices rise again.

Who Determines Fuel Economy?

Fuel economy numbers do not come from the automaker. Instead, just like with crash test ratings, the government steps in to perform testing and come up with a vehicle’s fuel economy. The Environmental Protection Agency (EPA) is the group in charge of conducting these tests.

All tests are performed at the Vehicle and Fuel Emissions Laboratory in Ann Arbor, Michigan where they have specialized equipment and a trained staff. There are strict regulations about how these tests are done to ensure consistency.

Over the years, the EPA has updated the information shown on the sticker as well as their testing methods. Better technology offers more accurate numbers and better labeling makes it easier for people to understand. The sticker design and testing methods performed today were last updated in 2011.

The window sticker on your new car provides the EPA fuel economy estimates for how many miles per gallon (MPG) your car will achieve. The label looks basically the same on every car so it’s easy for you to see the difference between cars. Here’s a breakdown of the information on those labels.

City MPG

This number represents the fuel economy you can expect in city driving. Think of city driving as just about any driving you do when you’re not cruising the highway.

Congested rush hour traffic that is lots of stop-and-go and streets with traffic lights and slow-moving traffic are all figured into this number.

Highway MPG

Highway MPG is usually the higher number and it represents the fuel economy you can expect to get when you’re driving down the highway. This covers driving when the speed is consistent.

Combined Fuel Economy

No one drives only in the city or only on the highway. Real world driving is some combination of the two, so the EPA also comes up with a combined MPG number.

The combined fuel economy falls somewhere between city and highway numbers and is the best way to compare one car to another. It’s the biggest number on the window sticker because it’s the one that should be the focus of your attention.

Looking for a new or used car? Check out BestRide’s listing search here.

Hydrogen Fuel Cell Label

Annual Fuel Cost

Do not look at this number and instantly assume that this is how much you’ll pay to gas up for the year. It’s an estimate based on very specific conditions.

It starts with assuming you are driving 15,000 miles. If you drive more, then that cost is going to go up. Think carefully about how much your drive when you figure out your fuel costs.

It also assumes a projected gasoline price, but that price is only an estimate. You may pay more or less for gas in your area than is typical elsewhere in the country, making this number inaccurate.

Instead of relying on the estimated fuel cost on the sticker, look at gas prices where you live and the miles you expect to drive then do the math to figure out how much you’ll spend on fuel in a year.

Your Savings over Five Years

This takes all those ratings and puts a dollar sign on them so you can see how much you’ll save by purchasing a more fuel efficient car. Alternately it will show you how much extra you’ll spend by buying a car with lower fuel economy.

It uses the same assumptions used to estimate the fuel cost. That means the number reflects 15,000 miles of driving a year and a projected gasoline price. Adjust the number accordingly for how much you drive and your local gas prices.

Comparison Numbers

These numbers make it easy for you to quickly judge how your car compares with other competitive models. This is shown with a range of fuel economy numbers for other cars in the same class.

A car that falls at the bottom of the range leaves you plenty of shopping choices that will do better. A car at the top means you’re not going to do much better and you’re getting a very fuel efficient car for the class.

Diesel Label

Environmental Ratings

The EPA also assigns both a Fuel Economy and Greenhouse Gas Rating and a Smog Rating on a scale of 1-10. Although this number doesn’t matter as far as how much you’ll pay for fuel, it does show the potential environmental impact of driving a less fuel efficient car.

Vehicles that run on either diesel or compressed natural gas have a third rating for CO2 emissions. Each label clearly indicates a vehicle’s fuel type in the upper right corner in a blue box.

Hybrid Label

Driving Range

Electric, hybrid, hydrogen, compressed natural gas, and some flex-fuel vehicles also include a driving range. The driving range lets you know how far you can get using the combined sources together.

This lets you more easily judge costs. You can see how for you can go on gas only versus both gas and electric on a hybrid, which can be helpful in estimating your fuel costs.

What is MPGe

An increasing number of cars run on more than just gasoline or diesel. That “e” stands for “equivalent” and takes into account how far your car will travel on other sources like hydrogen or electricity.

This gives a number far higher than you’ll see on a traditional gas or diesel vehicles.

All the Numbers are Estimates

There is no way to know exactly what kind of fuel economy you will achieve in your new car. All the testing in the world can’t get an exact, guaranteed number.

The fuel economy estimates are only estimates. Your fuel economy will be close, but it might fall below or above depending on how you drive and how you maintain your car.

The EPA estimates are intended to be a guide and help you make an informed choice, but it’s important to consider how you drive when you weigh the fuel economy decision.

If you do lots of highway driving, your numbers may skew high. If you’re a very aggressive driver who loves to slam that gas pedal down, then your numbers will skew low. Think about your driving style and the type of driving you’ll be doing when you’re figuring out if a car’s fuel economy will work for your personal budget.

Looking for a new or used car? Check out BestRide’s listing search here.