Alternators

OAP/OAD

Overrunning alternator pulley/Overrunning alternator decoupler

http://ww2.gates.com/europe/OAP/index.html

http://www.daycoproducts.com/what-are-oaps-and-oads-and-how-do-they-fail

1% fuel savings?

http://www.eurekamagazine.co.uk/design-engineering-features/technology/overrunning-alternator-pulley-improves-internal-combustion-engine/39568/