Auto Tech

EPA confused by Chevy Volt's fuel economy

The EPA is not sure how to rate the upcoming Chevy Volt's fuel economy, and GM's not happy about it.

General Motor Co.

The EPA is not sure how to rate the Chevrolet Volt's fuel economy, and GM isn't at all happy about it.

According to Motor Trend, the confusion stems from the EPA's classification of the Volt. Is it an electric vehicle (EV) with an onboard generator, or a hybrid vehicle that relies heavily on its electric drive? It's actually a little of both and a little of neither. The driving habits and battery-charging routines of the operator play a huge role in the classification of the Volt.

The way the Volt is designed, the wheels are powered by the electric motor and lithium-ion battery pack. When the batteries run low, the gasoline engine kicks in to extend the range. There is no direct connection between the internal combustion engine and the wheels. If the driver's commute is longer, driving is more aggressive, or if no plug-in option is available, the Volt will have to use its gasoline engine to keep the batteries charged, behaving more like a hybrid in this scenario. If the driver has a short commute, takes it easy on the accelerator, and plugs in to recharge the battery during the day, the Volt will operate primarily as an EV, and the gasoline engine's role will be greatly diminished.

In this configuration, the Volt can slip through about 85 percent of the EPA's test cycle without even firing up the gasoline engine. Using the EPA's standard formulas to calculate fuel economy, the Volt averages over 100 mpg. The EPA doesn't think that astronomical number is fair and has revised its tests with the requirement that the Volt finish the test with its batteries close to full charge, which means the internal combustion engine must run for the entirety of the test, dropping fuel economy to about 48 mpg.

GM, of course, argues back that the EPA's new test isn't fair because the test isn't representative of the way the Volt was designed to operate and doesn't reflect the Volt's plug-in option for battery charging.

The truth lies somewhere in between, but the EPA rating assigned will play a big role in whether consumers think the $40,000 Volt is a good deal compared with the Toyota Prius and the upcoming, and even less expensive Honda Insight.