People who care the most about getting great gas mileage may be disappointed to learn what Consumer Reports' latest tests have uncovered. It turns out hybrids-while some of the most fuel-efficient cars on the road-are all too often coming up short.
When you're shopping for a new car, the window sticker says how many miles per gallon you can expect to get.
Those numbers are an estimate based on tests developed by the Environmental Protection Agency.
But when Consumer Reports ran its own fuel economy tests on 315 cars, the results for many hybrids were surprising.
Rik Paul of Consumer Reports says, "Hybrids tend to be very fuel-efficient. But many of those we tested got far fewer miles per gallon than their window stickers claim."
For example, the Ford C-Max hybrid-the EPA says it gets 47 miles per gallon overall. Still good, but about 21 percent less than the EPA estimate.
Paul says, "We think the problem is that the EPA ratings are based on outdated tests that don't reflect real-world driving conditions for hybrids."
Take highway driving, one of the tests the EPA performs on this "dynamometer." It tests cars at simulated speeds that average just 48 miles per hour-with a lot of stop and go.
Paul says, "Hybrids do well in those driving conditions. They can often operate in electric mode without burning any gas."
But Consumer Reports tests highway mileage on a highway, at a steady 65 miles per hour. Technicians install a fuel meter to measure the amount of gas burned.
Paul says, "In those conditions, hybrids are constantly running their gas engine, so they burn more gas than they do in the EPA tests."
Consumer Reports has discussed its findings with the EPA, and the agency says it's considering updating its tests.
Following Consumer Reports' investigation, Ford says it will be offering free software upgrades to owners of its 2013 hybrid vehicles. Ford says the changes are designed to improve mileage in real-world driving situations.