sample-epa-fuel-economy-labelFor many customers searching for a new car, the big numbers on the EPA fuel economy label are often the first thing they see when browsing an auto dealer’s lot – and it’s one of the easiest ways to quickly compare the efficiency of several cars side-by-side. Consumers say that fuel economy is among their top concerns when making car-buying decisions. So it is critical for those labels to accurately estimate the mileage a new owner should expect.

This begs the question:  how accurate are the EPA fuel economy labels?

Consumer Reports tests dozens of cars a year, using precise tools to collect extensive data on each of the vehicles tested. We also have a highly informed subscriber base that answers detailed survey questions about their own vehicles. This allows our researchers to compare CR’s test results and owner-reported mileage with the EPA labels to see if the numbers are similar.

When Consumer Reports first conducted this analysis in 2005, we found substantial differences in our test results compared with the EPA’s labels — the average difference was more 10% from the CR tests. Much of the inconsistency was the result of outdated procedures by the EPA that didn’t reflect real-world driving situations. Following CR’s report, EPA updated their testing procedures to accommodate faster driving speeds, acceleration, air conditioning use and colder temperatures.

These updates made a big difference. Based on nearly 400 vehicles from model years 2009 to 2016, the average gap between CR’s tests and the EPA label was approximately 3%, a significant improvement that translates to an average difference of only 0.8 MPG on the label.

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.  However, based on CR’s survey results, hybrid owners reported higher average efficiency that was more in line with EPA estimates.

One thing is clear – for most car buyers, what you see on the label is very likely to be similar to what you get on the road. And EPA’s most recent update is even more consumer-friendly, allowing you to quickly see a given vehicle’s expected annual fuel costs and savings compared to the average new car.

To learn more about EPA’s new labels, visit fueleconomy.gov.

Click here to read the full Consumer Reports fuel economy label analysis.