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Edmunds has posted a fine article about the new EPA fuel economy ratings.
Car buyers shopping for fuel economy this year should expect to see some unexpectedly low mpg figures on 2008 models, some of which are hitting showrooms now. Don't get all stressed. New cars have not suddenly become thirstier.
Starting with 2008 models (which went on sale as early as January 2, 2007), the methodology for measuring and reporting fuel economy has been reworked to make published miles-per-gallon (mpg) ratings more accurate. The trouble for consumers is this: 2007 models and leftover 2006 vehicles on the lot next to the '08s will appear to have superior fuel economy. But they don't. This conundrum exists because 2007-and-earlier models use an Environmental Protection Agency (EPA) fuel economy measurement that is being phased out.
Your mileage has varied
For years, consumers have groused that their new car simply can't match the gas mileage estimates displayed on the window sticker or featured in advertisements. The typical gut reaction has been to blame the carmaker, attributing the shortfall to an overenthusiastic marketing department. We see this type of comment all the time in our forums, and it seems that no company - even hybrid car manufacturers - is immune.
Hybrids take the biggest hit
Taken together, the higher speeds, use of air-conditioning, hot and cold temperatures and more aggressive acceleration and braking will bring 2008 ratings down. According to the EPA, city ratings will drop about 12 percent, with some losing as much as 30 percent. Highway ratings should fall an average of 8 percent, but could drop by up to 25 percent.
Ironically, smaller cars oriented toward fuel economy take the biggest hit, with hybrids drawing the shortest of all straws. Why? Assuming that the fuel economy on both vehicles drops the same percentage, a car that gets 40 mpg will lose more actual miles per gallon than one rated at 14 mpg. Also, smaller-engine cars have to work harder to accelerate more swiftly, particularly with the air-conditioner on.
For hybrids it can be worse, as the additional demand caused by air-conditioner use, strong acceleration or high-speed driving reduces the amount of electric-only operation. And as you might expect, more fuel is consumed whenever the gasoline engine is required to power up.
On the braking side, the old test's mild deceleration rates allowed hybrid cars' regenerative braking systems to absorb more energy and store it in the batteries. The sharper deceleration rates now specified require more liberal use of the brake pedal, leaving less braking energy for the regenerative system to capture.
I feel a public education campaign would have been more effective. An education campaign would save many barrels of oil and increase morale of the driving public. The only disadvantage to teaching people how to drive more efficiently is, less tax revenue.
The labels were never designed to tell people what to expect from their vehicles in regards to fuel economy. They were designed to assist consumers trying to buy a new car or truck to compare vehicles with some sort of apples-to-apples system. Suppose I am looking for a vehicle and I've narrowed my choices down to car A and car B. I see that car A gets 51 mpg on the highway test and car B gets 39 mpg on the highway test cycle. I would be more likely to choose car A. Then I'd see the fine print YMMV - your mileage may vary (at some point it became your mileage WILL vary). After considering all of the variables I would choose on the Prius car A.
Under the new test the city mileage of the Prius is expected to drop from 60 mpg to the high forties .
Now that the resources have been spent on redoing the labels, maybe we'll also see some sort of driver education campaign trying to get drivers to drive more efficiently.
Kacey Green
www.GRLT.com, www.FLhybrid.com
"Tech with a twist of lime!", "Promoting the spread of clean personal transportation technologies."
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