Stop-start technology has been available on numerous European automobiles for some time, and, according to Hybrid Cars, the fuel-saving tech is projected to be offered on up to 42 percent of vehicles in the U.S. by 2016. However, there are virtually no incentives pushing automakers to equip U.S.-bound models with auto stop-start, and there is one regulatory reason for them not to focus on offering this option.
The problem is that the EPA's current testing methods don't accurately assess the real-world fuel-saving benefits of stop-start technology, which shuts the engine off when the vehicle is stopped. The EPA only has limited idle time built into their fuel use tests, which means that most models equipped with start-stop get absolutely no bump in their official fuel economy ratings. Without any sort of official support, automakers see no boost in CAFE numbers for their start-stop vehicles. Currently, only three non-hybrid vehicles sold in the U.S. – the BMW M3, the Porsche Cayenne and Porsche Panamera – feature stop-start technology.
The lack of incentives, according to John Gartner, an analyst at Pike Research, will likely keep most automakers from equipping U.S. models with stop-start tech. However, Gartner claims that most American buyers would "embrace vehicles that don't burn fuel when stopped" if they were available.
[Source: Hybrid Cars]