Car lovers rate auto expositions on the number and kinds of automobiles displayed on convention hall floors.

But convention and tourism officials use a different measure. To them, a car show is one of many trade events competing for convention dates and floor space. The winner is the one that puts the most heads in hotel beds.

Trade shows that fill hotel rooms for two or three nights are especially desirable. The longer visitors stay in town, the more money they are likely to spend at and apart from the event that brought them there.

By comparison, events that fill convention halls during the day but leave hotel rooms vacant at night can cost more than they earn. City services, including police protection, are expensive. Convention hall lights don't burn free of charge.

Given those realities, convention and tourism officials, including those at the Washington Convention and Tourism Corp., tend to be a conservative lot. They stick with what works -- even if it is only modestly successful.

That, mostly, is why the Washington Auto Show has remained unchanged for 62 years. It was conceived as Christmas holiday fare, served to families in town for the annual yuletide celebration. Thus, the shows began at or shortly before Christmas and ended on New Year's Day.

That made sense in decades past. Washington was a sleepy Southern outpost that happened to be the nation's capital. Hotel beds were easy to fill, because the hotels weren't many. With Congress, lobbyists and federal regulators out of town for the holidays, hoteliers were happy to have a few ordinary souls pick up the slack and flop in their sacks.

But times have changed, and the WCTC, the authority controlling convention booking dates in the District, is giving the Washington Auto Show a big chance to change, too.

The WCTC and the Washington Area New Automobile Dealers Association (WANADA), the latter being the primary sponsor of the auto show, have confirmed that new show dates will be set for later in January, beginning Jan. 23-29, 2006.

Confirmation also came from Yoffe Exposition Services Inc. of Marblehead, Mass., the company that actually sets up the Washington Auto Show and numerous other expositions worldwide.

There was an attempt to establish those dates for 2005, but the 2004 presidential race got in the way of that. The winner of that contest will be dancing at inaugural balls in January 2005. Local hoteliers won't have any problems finding customers then.

So, the 2005 show will follow the traditional schedule, which means it will run Dec. 26, 2004, through Jan. 2, 2005, for the general public.

The new schedule starting in 2006 will be in effect through 2009. It is a chance to turn the Washington Auto Show into a premier automotive exhibition by taking advantage of Washington's strengths, said Bob Yoffe, president of Yoffe Exposition Services and director of the Washington Auto Show.

"We're putting together a good plan to create a world-class auto show. The convention authority is working with us, giving us a chance to prove ourselves with this new schedule," Yoffe said.

The plan is to exploit Washington's position as the top regulator of all things automotive in the United States.

Washington has the White House, Congress, the Environmental Protection Agency and the National Highway Traffic Safety Administration. It has the lobbying office of every major automaker in the world, and it also is home to many lobbyists for every major group working against them.

The problem with the traditional Washington Auto Show dates is that few if any of those people are around town during the Christmas holiday period. They are back in their districts, or otherwise away from here with their constituents, families and friends.

Indeed, I always find more members of Congress and federal regulators attending car shows in Detroit, New York and Geneva than I do at the show in Washington.

For the car companies, that makes the D.C. show something of a downer. It costs them tens of millions of dollars to set up exhibits. The aim is to get customers. But it's also to influence policy by demonstrating things such as new safety, fuel conservation and emission-control technologies. In that regard, over the Christmas holidays, they quite literally are playing to an empty House and Senate in Washington.

The 2006 event will include a Congressional Day on Jan. 23. The initial aim, of course, is schmoozing -- giving lawmakers personal access to the auto industry's movers and shakers, engineers, designers and chassis makers. But the plan is for Congressional Day to eventually grow into a genuine federal-corporate-citizen automotive seminar to discuss and debate a wide range of industry topics.

That should help to bring a lot of industry analysts, engineers, suppliers, designers, journalists and others to town to help fill more hotel beds.

Plans also are in the works to make Washington's Embassy Row an integral part of the auto show. China, for example, is emerging as a global player in the industry. It should have display space there. Ditto Russia, India, Poland, Brazil and many others.

Plans also include possible display space for alternative automobile companies, such as Zap, the electric car producer in Santa Rosa, Calif.

In short, if it all works out, local hoteliers will be happy. But, more important, car lovers will be happy. They finally will get the Washington Auto Show they have been demanding for years.

The Washington Auto Show has traditionally been a largely local affair, falling between Christmas and New Year's. Organizers plan to change that.