From the Mitsu engine thread:
Smart ForTwo to share engine with Mitsubishi and Nissan; Joint development could help Smart to break even in 2007.(Brief Article)
Automotive News Europe, April, 2005 by Meiners, Jens
Byline: Jens Meiners When DaimlerChrysler announced its turnaround plan for Smart on April 1, it said the next gasoline three-cylinder engine would be used by other companies. That engine will be a unit jointly developed by Smart and Mitsubishi. Sources say Mitsubishi will build it in Japan and sell it to Nissan.
The engine will be used in the next-generation Smart ForTwo due in the third quarter of 2006 [OK, a few years late], and in Japanese-market microcars from Mitsubishi and Nissan.