No, it's not because it's ineffective or too expensive. In fact, it doesn't really cost all that much and it does help improve overall economy. The problem is the EPA test cycle.

At least that's what Mazda's product development chief Robert Davis told Automotive News. He said that because the EPA test cycle doesn't reveal any benefits of shutting down the engine when a vehicle stops, the technology doesn't improve official window sticker numbers. And if the numbers aren't there why bother having it?

We would like to think that consumers would be smart enough to know the difference, but we know Mr. Davis is right. If it's not there on the window sticker, most buyers will adopt there's no improvement no matter what explanation you give them.

Automotive News