ANN ARBOR — The Center for Automotive Research has decided not to hold a fourth annual Business of Plugging In hybrid and electric vehicle conference later this year.

A combination of declining attendance, a lack of enthusiasm about current prospects for electric and plug-in hybrid cars and a lack of sponsor funding combined to do in the event, said Brett Smith, co-director of the conference group at CAR.

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The event drew upwards of 700 attendees its first two years but attendance slumped to 400 last year.

“As we’ve seen from the marketplace, the business model is not ready for prime time,” Smith said. “The intent of the conference was to push the industry to understand that there needs to be a business case for this. It can’t just be something that the government or politicians want to happen.”

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That’s been accomplished by the market, where Chevrolet Volt sales are below projections and Massachusetts-based A123 systems announced a $55 million battery recall Monday. Smith said EV developers are “much more cautious than they were two, three, four years ago.”

The first year of the conference was funded as part of a Michigan Public Service Commission grant to DTE Energy and General Motors. CAR simply ran the conference. The past two years, Smith said, CAR took over the entire event.

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CAR said it continues to study advanced powertrain technology trends, and will work to offer events that reflect the needs of industry stakeholders. For example, the Advanced Powertrain Forum at the CAR Management Briefing Seminars, Aug. 6-10 in Traverse City, will include a session focused on the plug in electric vehicle technologies as part of a broader look at powertrain technology and strategy. Registration for MBS is now open at