GreenHybrid - Hybrid Cars - View Single Post - Carbon measured as a part of EPA mpg Test

lars-ss · #28 (**permalink**) 07-14-2005, 11:10 AM

Here is a story which says basically what I was trying to say in a more concise way than my efforts:

http://www.autosafety.org/article.php?scid=77&did=854

Quote:

Outdated procedure

All vehicles - from gas-guzzling Hummer H2s to fuel-sipping Priuses - fare better on the test than they do on the road. But because mileage ratings are much higher for fuel-efficient cars, a small percentage discrepancy can translate into a big mileage difference between the test results and reality.

The discrepancy stems from an outdated EPA testing procedure that was created nearly 40 years ago and that does not reflect accurately today's driving styles or routes.

"It was developed in the 1960s, when there were limitations on the test equipment at the time," Hermance said in an interview at the recent EVS-20 electric vehicle convention in Long Beach, Calif.

"They couldn't even brake hard because the testing equipment couldn't handle it. It really is 50th-percentile driving. No one drives like that anymore."

But certain loads, such as running the air conditioning, are not considered. Neither is cold weather, which disproportionately penalizes battery-powered vehicles more than internal-combustion ones.

Dan Harrison, manager of the vehicle programs group for the EPA in Washington, admits that hybrids are difficult to test because "there are more variables with a hybrid than with an internal combustion engine."

For instance, hybrids also must account for regenerative braking and the load accessories place on the vehicle.