Analysis: EPA Revising Fuel Economy Testing Guidelines

After a series of scandals involving incorrect fuel economy ratings, the EPA is revising its self-reporting guidelines for auto maker fuel economy standards, in a bid to ensure greater accuracy in the real world.

Currently, manufacturers are responsible for conducting their own tests according to EPA guidelines. While the new regulations cover the preparation of the vehicle in advance of the test, the Detroit News also reports that a key metric is being revised to closer match real world driving conditions

Also at issue are “road load” tests used to determine the impact of aerodynamic drag and tire rolling resistance on gas mileage. Currently, that is measured at 50 miles per hour. Under the new guidelines, automakers must measure the results at all speeds up to 70 mph.

The relatively slow speeds can often equal a highway fuel economy figure that is optimistic compared to what drivers can expect in real world conditions. The EPA also intends to close the loophole used by Ford that allowed it to assign the same fuel economy ratings for the C-Max and Fusion Hybrid models. This loophole allows auto makers to state the fuel economy rating of the “volume” model for a group of vehicles that use the same powertrain. In this case, Ford was able to use the superior Fusion’s rating for the C-Max (which got 43 mpg to the Fusion’s 47). Ford ended up re-stating fuel economy figures for the C-Max and compensating owners for delivering poorer than advertised fuel economy.

But the new guidelines are just that. Speaking to the paper, the EPA’s Chris Grundler said that drafting new, legally binding rules would take two to three years, which is too much time in their eyes

“Writing regulations takes time…When you are working in the rapidly changing environment that we’re in right now, we want to make sure that we are agile enough and flexible enough to change with those times.”

As we’ve noted in the past, the EPA’s fuel economy standards need a significant overhaul. The new “guidelines” simply don’t go far enough. The EPA only audits around 10 to 15 percent of vehicles per year, relying on the manufacturers to provide accurate claims for the rest of the fleet. Meanwhile, the test procedures themselves can be gamed due to powertrain calibration that takes advantage of the test parameters.

The test itself, as some have suggested, is really oriented more towards emissions than fuel consumption. If that’s the case, why not overhaul it to be more like the European tests that measure CO2 – which happen to be undergoing their own revamping right now to better ensure real world relevance? Both tests also give far too much leeway to small turbocharged engines, which are notorious for performing well on the test and then wildly missing their stated fuel economy in the real world.

With fuel economy figures becoming an increasingly important part of consumer decision-making – and auto maker marketing campaigns, the need for a more accurate fuel economy testing procedure has never been greater. The new guidelines are a step in the right direction, if nothing else. But they could go further.