What Are the Most Inaccurate Numbers on the Window Sticker?


Virtually everything on the Monroney sticker can be negotiated.

The Monroney, better known simply as the window sticker that adorns all new cars for sale, tells vital information about the vehicle, its engine size, trim level, installed options, and, of course, the manufacturer’s suggested retail price (MSRP).

The listed price is typically a starting point for negotiation, and the sticker will tell buyers of any added market adjustments or unnecessary options.

There’s one number, though, that isn’t negotiable and has a long reputation of not even being accurate:

The EPA estimated fuel economy.

In 2005 Consumer Reports published research on a study that tested the EPA ratings on cars from model years 2000–2006.

The results showed an alarming difference between the estimates and real-world fuel-economy results. Since the EPA didn’t account for summer driving with the air conditioner on, or the fact that the majority of cars in the U.S. have to deal with winter weather, the estimates differed from real-world driving by an average of 10.3 percent, or 3.3 miles per gallon.

The EPA has earned a more respectable grade this time around. CR found that on 397 vehicles, the difference between the regulator’s estimate and the results of its own testing amounted to just an 0.8 mpg difference.

While 57 percent of vehicles tested by Consumer Reports saw actual fuel-economy numbers come in lower than the EPA estimates, the publication noted that over 80 percent of the real-world fuel economy results were within 1 mpg of the EPA’s best guess. The published article says,

Like the 2005 analysis, the accuracy of EPA labels varies by engine type. CR tests found conventional gasoline engine were approximately 0.7 MPG less efficient compared to the EPA label, while diesel engines were about 0.7 MPG more efficient than the label. And testing procedures for hybrid engines may need further refinement—the average difference between EPA labels and CR tests was approximately 3.3 MPG (9.1%), even in the new analysis.

This comes just as the EPA will again change its methodology for providing fuel-economy estimates on 2017 vehicles. We expect the ratings on mechanically unchanged vehicles to drop slightly while estimates on new engines should come even closer to reality.

For now, it seems the only number on the sticker that is completely accurate is the engine size. Everything else, including the price and the fuel-economy estimates, are probably inflated, even if just by a hair.

How important are fuel-economy estimates when you’re shopping for a new car?


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