Global auto manufacturers have made considerable progress in increasing fuel economy and reducing nitrogen oxide (NOx) emissions, and experts at Emissions Analytics see the U.S. getting closer to 2025 federal fuel economy targets by adopting approaches from Europe.
The Corporate Average Fuel Economy (CAFE) target of 54.5 miles per gallon by 2025 is actually the equivalent of an EPA sticker fuel economy of about 41 mpg (nearly 20 percent lower because of the manner in which they are calculated). U.S. passenger cars and light trucks tested by Emissions Analytics currently achieve 24.9 mpg in real-world driving, which will require a two-thirds increase to get to the target. By contrast, Europe already is achieving 36.8 mpg.
From its extensive database of test results, Emissions Analytics calculates that the U.S. could raise its sticker fuel economy by 4.6 mpg to 29.5 mpg by switching to smaller 4-cylinder engines and other downsizing technologies, according to Nick Molden, CEO of U.K.-based Emissions Analytics. Adopting more fuel-efficient European technologies such as direct injection and variable cylinder technology could add a further 3.7 mpg to reach 33.2 mpg. To match the European 36.8 mpg, an additional 3.6 mpg could be achieved by adding more diesel engines to the mix.
“That only leaves less than three mpg in fuel economy to hit the target,” Molden said. He adds that he is encouraged by the progress made by automakers in the pursuit of greater fuel economy and reduced emissions. “The potential for further strides is clear from international experience.”
He pointed out that “there is a race on in Europe to see if advances aimed at cleaning up diesel emissions will be sufficient to open up the CO2 and fuel economy advantages of these power plants, especially in light of significant under reporting of NOx emissions by Volkswagen’s engine-management software. If not, further gasoline hybridization will be needed for the U.S. to get to its 41 mpg target.”
On the emissions front, new European Commission rules will include “real world” vehicle emission tests beginning in 2017. Passenger cars in Europe will undergo mandatory Real Driving Emissions (RDE) on-the-road tests using a portable emissions measurement system – the first time NOx will be measured outside of a laboratory.
Molden pointed out that European automakers also have made progress in meeting Euro 6 standards adopted last year that lowered allowable NOx emissions by more than 50 percent. Test data from Emissions Analytics, however, clearly shows wide variations between laboratory results and actual real-world vehicle emissions.
The RDE tests are designed to eliminate the discrepancy between lab testing and results from real-world, on-road testing. Molden said the call for “real-world” emissions data, which is growing because of the VW scandal, actually could spark further meaningful reductions in vehicle emissions.
“Our research indicates that Euro 6 diesel passenger-car engines have shown a 49 percent reduction in NOx emissions compared to Euro 5 diesels,” he said. “We believe automakers anticipated the tougher requirements and really stepped up their game with regard to emissions. The early results are encouraging, yet we feel they are still mixed.”
In a recent project sponsored by the London Sunday Times, for example, Emissions Analytics data showed that Euro 6 diesel cars actually produced NOx emissions 4.4 times higher than the legal European Commission standards.
As the leading provider of real-world emissions data, Emissions Analytics has compiled test results on more than 400 diesel-powered cars manufactured in Europe and the U.S.
Although its recent Euro 6 diesel tests showed marked improvement in NOx emissions, those vehicles still scored NOx levels just under four times higher than the legal limit of 0.08g/km. However, it was a significant improvement over last year’s International Council on Clean Transportation report showing that Euro 6 diesels produced NOx emissions that were on average 7.1 times higher than legal limits.
“We think the decision to add on-road testing by the European Commission and member states was a good one,” said Molden. “We started testing tailpipe emissions on the road four years ago. Based on our test results, we’ve felt strongly that this is the only way to truly understand real-world performance. It is good to see this method is now being recognized as a result of the action taken by the commission.”