EPA Proposes New Methods for Estimating Fuel Economy
10 January 2006
|One of four proposed new fuel economy labels|
The EPA today proposed new rule and test methods for calculating fuel economy estimates, as well as four options for a new design of the fuel economy label that will provide a more quantitative view of “your mileage may vary.”
EPA’s goal is to bring the MPG estimates closer to the fuel economy consumers actually achieve on the road. The new MPG estimates will take effect with model year 2008 vehicles, which will be available in dealer showrooms in the fall of 2007.
Currently, mileage estimates come from data from two laboratory tests which were last revised in 1985. At that time, the fuel economy figures derived from those test were adjusted downward—10% for city and 22% for highway—to more accurately reflect driving styles and conditions.
Current test are run under mild temperatures without the use of accessories such as air conditioning, and with sedate acceleration and speeds capped at 60 mph.
That’s not the case for emissions tests, which have been enhanced since the mid-1990s to require the use of a much broader range of real-world driving conditions, such as high-speed, fast-acceleration driving and the use of air conditioning and colder temperature operation (20º F).
These conditions and behaviors not only affect the amount of emissions, they also have a significant impact on fuel economy.
EPA is proposing the incorporation of those tests into the methods used to determine the fuel economy estimates posted on the window stickers of new cars and light trucks. EPA is also proposing that the fuel economy estimates reflect other conditions such as road grade, wind, tire pressure, load, and the effects of different fuel properties.
In 2011, another provision would require manufacturers to perform additional cold temperature, air conditioning and/or high speed/rapid acceleration driving tests for some vehicles that may be more sensitive to these conditions.
The fuel economy for each vehicle model would continue to be presented to consumers as city and highway MPG estimates.
Under the new methods, fuel economy ratings will drop for most vehicles. EPA estimates conventional (non-hybrid) vehicles would drop on average by about 10–20% from today’s labels, while the highway estimates would drop by about 5–15%, depending on the vehicle.
For hybrid vehicles, the city MPG estimates would drop 20–30% from today’s labels. For highway MPG estimates, the change is about the same as for conventional vehicles. The nature of current hybrid technology— the addition of a battery as a second source of on-board power, sophisticated control systems, and sometimes a smaller engine—makes a hybrid’s fuel economy more sensitive to certain factors, such as colder weather and air conditioning use.
EPA is providing sixty (60) days for the public to submit written comments on this proposal, including comments on the proposed label designs.
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