For years, the glitzy charity preview of the North American International Auto Show was the hottest ticket in Detroit. With tax-deductible tickets costing $400 each, the event stands as the industry's biggest social event of the year.

But proceeds and attendance were down in 2007 from previous years. The preview raised $6 million for 11 local children's charities this year, down $800,000 from last year and about $1 million from 2005.

Critics say Michigan's harsh economy is not entirely to blame. Instead, they argue the event has become so crowded that many previous attendees have decided it's no longer worth the hassle.

Another problem: Some of Detroit's largest suppliers, which traditionally have purchased big blocks of tickets for employees and customers — say show organizers now won't give them the time of day.

The suppliers claim NAIAS officials repeatedly have snubbed them when they have asked to play a larger role in the auto show. Meanwhile, suppliers are more involved in the Frankfurt, Tokyo and Paris auto shows.

Robert Thibodeau Jr., senior co-chairman of NAIAS 2007, sees the glass as half full, pointing out the preview remains one of the largest charitable events of its kind in the U.S.

“We raised 6 million bucks in the face of a very tough economy,” Thibodeau says.