My understaning of the new SAE standards is this - that as new models and new engines are introduced, they are now tested with the updated standard. Re-testing of vehicles/engines already in the lineup is optional, and manufacturers may continue to use the old SAE standard until the model/engine is updated or discontinued. (I may very well be wrong about all of that)

Honda & Toyota chose to retest their entire linups with the new standards. Most domestics have only retested a few - as well as their new introductions, which obviously aren't going to "lose" power since they hadn't yet been rated in the first place. While it's nice that several domestic models have seen their ratings increase, I don't buy the whole "Asians overpromise domestics underpromise" thing until GM & Ford retest their entire lineup in order to do a more accurate comparison, which I understand they're not going to do unless they update the powertrains.

I'm not saying that the domestics are testing their vehicles and only releasing the numbers for powertrains that "improve," but the vehicles that they've hyped as having improved power numbers (Corvette Z06 500hp to 505hp, Dodge Viper 500hp to 510hp, Caddy STS-V 440hp to 469hp) have all been niche vehicles with burly powertrains in the first place. Gimme some domestic econo-car numbers for a real comparison.

http://www.detnews.com/2005/autosins...A01-283759.htm