How to Read the New Fuel Economy and Environment Labels

Let's start by looking at the parts of the label that have to do with fuel economy. We'll use the label for gasoline vehicles as an example, but most of the information is the same on the labels for other types of vehicles. In a few pages, we'll explain what the differences are.

The label header tells you what type of fuel the vehicle runs on -- in this case, gasoline. This information will mostly be useful to you if you don't know anything about the model you're looking at and there isn't a salesman around to answer questions.

Right below the header comes something far more important -- the fuel economy section of the label, which is the largest section by far of the new EPA label design. The upper left part of this section includes the same information we've been seeing on EPA labels for years -- the city, highway and combined mileage of the vehicle. The biggest change here is that the combined city/highway mileage is now in large print while on older labels it was in such tiny print you practically needed a magnifying glass to read it. The EPA's reasoning is that this figure provides the easiest method of comparing mileage between cars. Drivers who spend most of their time on the highway or in stop-and-go city traffic may disagree, but for most drivers this is probably a good assumption. Because this figure will vary according to driving style and commuter routes, it should be used strictly for comparison purposes between different models of car.

Beneath these figures is what the EPA calls the Fuel Consumption Rate, which they believe offers a much more accurate and easily understandable way to compare fuel efficiency than the MPG figures do. According to the EPA, that's because the relationship between MPG ratings and amount of fuel saved isn't linear, but decreases as the MPGs go up. For instance, as the EPA states on its Web site, the amount of gas saved over a 1,000-mile trip by a car that gets 15 miles per gallon compared to a car that gets 10 miles per gallon -- a 5 mpg difference -- is 33 gallons. But the amount of gas saved over that same trip by a car that gets 35 miles per gallon compared to a car that gets 30 miles per gallon -- also a 5 mpg difference -- is only 5 gallons, a much less significant difference. The EPA calls this the "MPG illusion" and it makes it difficult for a consumer to compare fuel efficiency between two cars merely by noting the difference in MPGs. The new labels avoid the MPG illusion by simply stating the number of gallons that every car will use (on average) over a fixed distance of 100 miles.

In the middle of the label is the EPA's description of the MPG range for the category that the vehicle belongs to (SUV, mid-sized car, etc.), so you can see how the vehicle compares to others in its class. Because not all cars use liquid fuels that can be measured in gallons, some of these figures will be based on the amount of energy that the EPA considers the equivalent of a gallon of gas. These figures are labeled using the term MPGe, which stands for "miles per gallon equivalent."

Probably the most eye-catching piece of information on this part of the label is the fuel-savings figure on the right and it's probably the one that the average prospective car buyer will be most interested in seeing. It gives you an estimate of how much money the car in question will help you save (or overspend) on gas over a five year period as compared with the average new vehicle. Now you might be asking yourself how in the world the EPA can know this. They don't know how many miles per year you drive or what the price of gas is going to be in a few months (or even in a few days) after that label goes on the car. They don't even know what price your local gas station charges per gallon. The answer is that the EPA is just guessing, but at least it's an educated guess, based on a couple of assumptions. The first is that you'll drive about 15,000 miles in a year. This may seem excessive -- some people drive barely a third that many miles in a year -- but the EPA uses this figure consistently for all cars, so this is another one of those numbers that's for comparison purposes only. Similarly, the EPA projects the price of gasoline over the next year based on reasonable assumptions (or maybe they just have a chimpanzee throw a dart at a list of prices?) and they use this figure consistently for all cars to calculate the average gas savings. There's a good chance you won't actually save as much on gas as the sticker says you will, but if you do an unusually large amount of driving and gas prices turn out to be unexpectedly high, you could conceivably save even more. If the projected 5-year cost of fuel for the car is better than average, this estimate will begin with the words "You save $x,xxx in fuel costs." If the cost is worse than average, it will begin with the dreaded phrase "You spend $x,xxx more in fuel costs." But what the heck -- it's your money.

The EPA label contains one more small section relating to fuel economy: annual fuel cost. This is the amount that you'll spend on gas in one year to keep the car running. It's based on the same assumptions as the fuel savings estimate -- that you'll be driving 15,000 miles annually and that the EPA has correctly calculated what the average price of gas is going to be over the next year. So, as you've probably guessed, this figure bears only a slight resemblance to reality and should be used for comparison purposes only.

And that's it for fuel economy. But the next part of the label contains information that many drivers will consider even more important, about the impact the car is likely to have on the environment.

Tucked down in the lower right portion of the label, where you might not even notice it beneath all those large numbers telling you about your mileage and gas savings, is the environmental impact section of the new EPA label. This part of the label is all about emissions from the car's tailpipe. Two horizontal bars rate the vehicle on a scale of 1 to 10 for greenhouse gases and smog, with 1 meaning that the car produces a huge amount of tailpipe pollution and 10 meaning that its emissions are very low and possibly even zero. There are several questions you might have about this. The first is: What's the difference between these two types of emissions? And the second is what do the numbers between 1 and 10 actually mean?

Greenhouse gases (which for cars generally refers to carbon dioxide, also known as CO2) are gases that, when they become part of the Earth's atmosphere, trap the heat of the sun and cause the air to become warmer. A certain quantity of greenhouse gases in the air is actually desirable, because without greenhouse gases the Earth would lose most of its heat into space, become covered with ice and we'd freeze to death. But our planet already has enough greenhouse gases to keep us warm and adding more gradually heats up the environment, leading to global warming and destructive climate change, so the closer this bar gets to 10, the better. You'll notice that the EPA combines fuel economy and greenhouse gas emissions into a single rating. That's because greenhouse gas emissions are directly proportional to fuel efficiency. But if 1 is the worst rating and 10 is the best, what do all the numbers in between mean? They're based on a chart created by the EPA that assigns numerical ratings to ranges of CO2 emissions, like this:

Rating	MPG	CO2 (g/mile)
10	38+	0-236
9	31-37	237-290
8	27-30	291-334
7	23-26	335-394
6	22	395-412
5	19-21	413-479
4	17-18	480-538
3	15-16	539-612
2	13-14	613-710
1	0-12	711+

So, for example, a car with a rating of 7 for fuel economy will get an estimated 23 to 26 miles per gallon of gas and will emit between 335 and 394 grams of CO2 per mile.

And what about that smog rating? Smog, in this instance, refers to gases such as nitrogen oxide, non-methane organic gas, carbon monoxide and formaldehyde, as well as particulate matter from partially burned fuel, that are released through the car's tailpipe. Once again, the worst rating is 1 and the best rating is 10.

Note that EPA is careful to specify that these are tailpipe emissions. Just because a car doesn't emit much in the way of pollutants from its tailpipe doesn't mean that pollution isn't produced in the manufacture of the fuel. This is even true for the electricity that powers electric cars. Usually the batteries in these cars are charged directly off the local power grid, which gets its electricity from power plants that may in turn use methods of generating electricity, such as coal burning, that themselves produce pollution.

Finally, there's the bottom of the label, which includes a much longer version of the traditional "Your mileage may vary" disclaimer, plus a brief explanation of how the information on the rest of the sticker was calculated. (The estimated numbers on this disclaimer will change over time, so the version shown here is just an example.)

The most important part of this section of the label is the Smartphone QR Code over on the right. (The term "QR Code" is a registered trademark of Denso Wave Incorporated and is an abbreviation for "Quick Response Code.") A QR Code is a form of barcode, like the ones that have appeared on product packages for several decades now. Traditional bar codes offer information one-dimensionally, in the widths (but not the heights) of the bars. That's why they can be read by devices that shine a single line of focused light across the codes. QR Codes, on the other hand, are two-dimensional barcodes, and contain data in the form of tiny squares arrayed horizontally and vertically across a larger square. QR Codes are complicated enough that it takes fairly sophisticated visual and computing equipment to read them, and so up until recently they've been used primarily for industrial purposes. But with the invention of modern smartphones, average people have started carrying around devices with sophisticated visual and computing equipment in them. Many smartphones now come with QR-reading apps preinstalled. If you have a smart phone without a QR reader already on it, you can download one from places like the Apple App Store (for iPhones) or the Android Marketplace (for Android phones).

To use your smartphone to read the QR Code on the EPA label, run the QR reader, tap whatever control causes it to scan a code, and aim your phone's camera at the lower right corner of the label. The QR reader should recognize the code (those big squares in three of the corners help it lock on to the image) and automatically snap a photo of it, which is then processed by the smartphone's internal computer. The reader will then print out the information contained in the code, which is usually text. This will in most cases be the URL of a special Web site that contains more up-to-date fuel economy information than is already on the sticker, using the latest gasoline prices rather than predictions made at the time the label was printed. Most QR Code reading programs will let you use your smartphone's browser to go directly to this Web site, so you can read it while car shopping.

Although the version of the EPA label that we've discussed over the last few pages is for cars that run on gasoline, most of the information will be identical for cars that use other types of fuel. On the next page we'll take a brief look at how the label can differ for cars that use other types of fuel.

At present, most cars use internal combustion engines and run on gasoline. Already, however, vehicles using alternative sources of power, such as battery electric and hybrid drivetrains, are starting to appear on the market. The EPA has designed the new label to accommodate several of these alternative fuels and the labels may differ for some of them. The most obvious difference will be at the top of the label, where the type of fuel is identified. For instance, this example identifies the vehicle as a plug-in hybrid. (There are also headers for flexible fuel gasoline-ethanol (E85) vehicles, diesel vehicles, compressed natural gas vehicles and hydrogen fuel-cell vehicles.) Most of these have labels modeled after the ones for gasoline-powered vehicles. The most significant difference in these alternate labels is in the fuel economy section of the hybrid-electric vehicle label.

This label is for a series plug-in hybrid. Because this form of hybrid runs on battery-powered electricity until the battery goes dead and then runs on gasoline, the sticker gives mileage for both forms of power, plus the time it takes to recharge the battery. Below this is a timeline showing how long it will run on battery power before it switches to a gasoline-powered engine. For parallel plug-in hybrids, which run on both electricity and gas until the battery goes dead, the timeline is somewhat different, showing how long the vehicle will run on a combination of power sources until switching over to just gasoline.

Pure battery-electric vehicles have a somewhat different fuel economy section. This is almost identical to the label for gasoline-driven vehicles, except that it measures kilowatt-hours used per 100 miles instead of gallons and has a timeline similar to that of the hybrid label, showing how far the vehicle can travel between charges.

And that should cover everything you'll need to know about EPA labels the next time you go auto shopping. Just remember to take your smartphone with you!

One of the great things about writing for the automotive section of HowStuffWorks.com is that I get a chance to learn about all the alternative fuel technologies that are being developed to increase the fuel economy and decrease the environmental impact of new cars. So it's exciting to see that the EPA has found a way to communicate information about the benefits of these new technologies to consumers directly on the fuel economy stickers of new cars. I'm also pretty excited to hear that the new EPA labels will give me yet another use for that smartphone I got on my last birthday and that those two-dimensional barcodes aren't just fuzzy-looking postage stamps.

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