Is your car or truck falling short of the fuel economy listed on its window sticker? According to the Environmental Protection Agency (EPA), it’s your fault!
In its own independent testing Consumer Reports magazine recently noted some vehicles equipped with downsized, turbocharged engines do not deliver real-world efficiency in line with what’s printed on their Monroneys.
This is an issue AutoGuide editors have noticed on multiple occasions as well. A recent example is the brand-new, 2013 Ford Fusion,which features Ford’s new EcoBoost turbocharged engine technology. During initial testing, indicated mileage was several points off what the car should have been delivering.
AutoGuide reached out to the EPA and asked why, on certain vehicles (particularly turbocharged ones), there can be such discrepancies between official and real-world numbers. An EPA spokeswoman responded via e-mail. “EPA is not aware of broad fuel-economy discrepancies due to turbocharging. Some turbocharged vehicles may be more sensitive to driver behavior than “conventional” vehicles. Driver behavior includes rapid acceleration, high speed, cargo mass, and towing.”
Why the added sensitivity compared to naturally aspirated engines? More directly, why is the driver to blame? According to the EPA so-called advanced-technology vehicles are more variable than conventional ones.
During testing on the US06 cycle, “higher loads” can cause forced-induction engines to operate at lower efficiency levels, levels nearer conventional engines. This seems to have a greater negative impact on their fuel-economy scores than their naturally aspirated counterparts. To keep things fair the same test cycle is used for both naturally aspirated and forced-induction vehicles.
Considering the observed issues with turbochargers, as more and more automakers downsize and crank up the boost, is the test is at risk of becoming irrelevant. The agency says that is not going to happen.
“[The] EPA will remain vigilant in updating fuel-economy labeling test procedures, proposing/implementing needed regulations, and conducting confirmatory testing.”
The EPA’s cycle is currently more accurate than it’s ever been. The rule was updated last year to accommodate plug-in hybrid and electric vehicles. Prior to that it was tweaked in 2008. For internal-combustion engines higher speeds and loads, air-conditioning usage and cold-weather variables were factored into the test.
Automakers are in a tough position. They have to balance ever-increasing safety standards against equally aggressive fuel-economy regulations. Vehicles get heavier and more feature laden with each generation, yet they’re expected to deliver better and better fuel economy. It’s a vehicular Catch-22, and one that shows no sign of abating.