Wired News points out how the EPA's new fuel economy testing will decrease the value proposition of hybrid cars. Its article, "Hybrid Cars' Fantasy Mileage Ratings Drive Into the Sunset," publishes estimated fuel economy numbers from Edmunds.com that show the Toyota Prius going from a combined city and highway 55mpg down to 46mpg. Similarly, it shows the going from a combined 50mpg to 42mpg. The estimations also show the standard gas engine Civic going from a combined 33mpg to 29mpg, as all cars, not just hybrids, are subject to the new testing procedures.
The Wired article doesn't do the simple math that shows the percentage decline: 16 percent for the Civic Hybrid and 12 percent for the standard Civic. Taken as a percentage, the numbers aren't quite as dramatic. Similarly, the standard Toyota Camry's economy goes down 11 percent, while the goes down by 13 percent. The EPA published its new fuel economy numbers for 2007 model year cars on its site. While the new tests better mirror the modern driving environment, your mileage will vary.