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.