According to Johnson Controls, stop-start technology can reduce a vehicle's fuel consumption by up to 12 percent. It's this benefit that has automakers racing to equip their vehicles with stop-start tech and Johnson Controls upping its investment to pump out more batteries. Molinaroli says that 80 percent of vehicles sold in Europe will be equipped with this fuel-saving system by 2016 and claims that, since batteries are still too costly, pure electric vehicles won't be mass produced until 2025. We have to assume he means on a bigger scale than, say, the Nissan Leaf and all the other EVs that are coming soon.
[Source: Ward's Auto – sub. req.]