They’ll roll out the finest automobiles again on the carpeted San Diego Convention Center floor and also give visitors a chance to test drive some of them outside the international auto show, scheduled for Dec. 31 to Jan. 4. Anything to sway, without selling, tight-fisted consumers toward thinking about going to dealership showrooms. No salesmen around. A little nudge but no push. The promoters encourage everyone to sit inside these newest models and touch those dreams.  More than 400 new model vehicles, concept cars and alternative fuel vehicles will be on display, encompassing more than 640,000 square feet. Ford, Hyundai and Toyota will hold ride and drive events outdoors. Ford and Hyundai will be located in the front of the convention near entrances F and A, and Toyota will be located behind the center. Showing off cars is one thing, but the big job follows in generating all feasible methods to spur dealership visits. And to spend wisely in promotions and advertising. Where, how and when does the industry get the biggest bang with an advertising budget? Automakers huddle with ad agencies to plot the most effective means of reaching the public Do they buy newspapers, magazines, television, radio or go online? Hard or subtle sales pitches? Anything but a giveaway to lure the customer to a showroom or lot. General Motors ended a seven-week experiment to sell new cars in California with eBay Inc. Many dealers reported the online marketplace didn’t help sell more vehicles and led shoppers to seek low-ball prices. But the experience illustrated why car retailing, which involves the tradition of haggling in person, makes an odd fit for the Web. Consumers expect to shop. GM sales chief Mark LaNeve said the program did generate customer interest, including 1.5 million visits to a special section of eBay’s Web site, and 15,000 customer leads for California dealers. He said GM hopes to try again next year. Over the past quarter century, Creative Broadcast Concepts has worked exclusively with some of the best automobile dealers in North America. During that time it has earned a reputation for being more like “car guys” than “ad guys.” In fact, one CBC client summed it up well when he said, “I can’t stand ad agencies. That’s why I hired CBC.”  CBC currently serves 50-plus clients in more than 125 dealerships across the U.S. and Canada. The automobile and advertising businesses have undergone more structural changes in the past 15 years than in the previous 85. By 2010, online reportedly will reach $4 billion, becoming the second-largest medium for automotive advertisers, surpassing newspapers, cable, radio, direct mail — everything but broadcast TV.  Car and truck advertising — from the automakers and dealer associations combined — fell 31.4 percent to $3.6 billion in the first six months of 2009. That’s down from $5.3 billion during the first half of 2008, according to The Nielsen Co., a New York audience and ad-spending tracking service. Total domestic advertising spending fell by $10.3 billion, to $56.9 billion, in the first half of 2009, Nielsen said. General Motors Co. and Chrysler Group both trimmed advertising during their respective bankruptcies.