Magnetti Marelli (read FCA) to supply Andretti, Dragon (read Penske), and Mahindra. Latter two expected to be based on the same base unit (a la the McLaren/Venturi/Mahindra unit in S2), while the Andretti is believed to be a different design to the other two.
http://current-e.com/chatter/magnett...ultiple-teams/