Idle-stop technology, which turns off a car’s engine instead of idling, is available from a number of automakers in the European and Japanese markets. Mazda claims nearly half of its Mazda3 compacts and Biante minivans sold in Japan are ordered with the $500 option, as consumers seek out fuel economy improvement without the cost of a full hybrid system. So, why doesn’t Mazda sell idle-stop equipped cars in the US? According to the company, though Japanese fuel economy tests show stop-start improving efficiency by seven to nine percent “the EPA city-mode test cycle includes only one complete vehicle stop, so stop-start technology registers only a 0.1- or 0.2-mpg improvement.” And who would pay $500 for that?
Mazda aren’t the only ones clamoring for an EPA rule change. Audi USA spokesfolks tell Automotive News [sub] that its idle-stop system “did not realize any savings in U.S. EPA estimates based on required testing cycles.” Automakers from BMW and Mercedes (which says it will offer stop-start on all its engines by 2011) to Kia, Honda and Toyota also offer the system in European markets, and could bring the systems to the US should the EPA decide to modify its testing to improve the impact of stop-start on official efficiency ratings. The EPA is reportedly taking public comment on rule changes that could do just that, providing automakers with the impetus to start bringing stop-start systems to the US market. Needless to say, this is something that should have been done yesterday.
Meanwhile, is it any surprise that none of the US-based manufacturers have invested in start-stop to the same extent as their European and Asian competitors? If and when the EPA does modify its test parameters to improve the impact of stop-start, it will be yet another opportunity for Detroit to fall further behind its foreign competitors.