Beyond the Sticker: How Efficient is Your Car?

EPA fuel economy numbers on window stickers have been the be-all and end-all measure of new vehicle efficiency in the United States since their inception in 1978.  But even after repeated updates of its procedure over the years, the EPA has been embarrassed by several instances of carmakers overstating the efficiency of its cars.  With more drivers tracking their own efficiency, and rising concern about pain at the pumps, there’s a growing outcry for more dependable estimates.

In most cases, the problem isn’t that the EPA testing process.  In fact, very few models go through EPA testing in a given year.  The numbers you see on a new car’s sticker are actually submitted by the carmaker.

The good news is that there are other sources of independent testing out there.  And now, thanks to a new partnership between Emissions Analytics, Intellichoice and Motor Trend, there’s one more.

The “Real MPG” procedure, as it’s being called, is based on 140 minutes of sophisticated testing using an array of sensors deployed on a test course designed to “realistically represent both city and highway driving.”  Roughly 100 new vehicles have been tested so far, and though the average discrepancy between the EPA numbers and Real MPG’s testing is marginal, some vehicles have shown as much as a 20-percent difference. 

Beyond the Numbers 

Even if there were no discrepancies between different testing procedures, the real-world performance of any vehicle would be subject to, let's be honest, how you drive.  Before making a purchase, every car shopper should do some driving self-assessment, and recalibrate expectations.  This holds true when you buy a 50-mpg Prius C (shown above), or a full-size SUV.  Here are a few things to consider:

City vs. Highway
The most important factor to consider is usually the breakdown of how many miles you drive in stop-and-go traffic, compared to miles you spend on the open road.  Using your trip computer or odometer to keep track of this over the course of a typical driving week should help you get an idea of any discrepancies between expectation and reality.  Gas- and diesel-fueled cars perform far better on the highway than in the city, while the extra cost of a hybrid will quickly pay for itself for heavy city drivers.

Can You Be Doing Better?
The efficiency of your car or truck is only as good as your personal driving style. With jack-rabbit starts, and aggressive quick braking, you’ll never achieve fuel economy numbers used in official ratings.  Be aware of your speed.  Use slow steady movements, and keep measuring until your fuel efficiency improves.

How much do you actually drive?
If you don’t drive very much, selecting a vehicle based on two extra MPGs of efficiency may not be the best economic decision.   On the other hand, if your daily driving is less than the range of a battery-electric vehicle, you might want to consider plugging in—and thereby cut your fuel use to nearly zero.