Economic impact. The consumer electronics industry continues to grow, to an estimated (by the Consumer Electronics Association) $170 billion in sales this year. But the auto industry, as they like to remind us, is bigger still, the car being our second biggest investment after a house. Sixteen million vehicles at an average price of $25,000 is on the order of $400 billion a year. Add commercial trucks and repair parts, and the auto industry is three to four times as big. Advantage: Detroit.

Future prospects for the show. CES, with 130,000 attendees (theoretically just trade, press, and analysts), faces only the possibility of Yogi Berra implosion ("so popular nobody goes there anymore") the way Comdex did five years ago when it grew too big, although the tech meltdown of 2001 had a lot to do with the Comdex fade, too. Detroit's future is more clouded, I believe, but it's not by the fact that Cobo Hall has 700,000 square feet to the Las Vegas Convention Center's 3.2 million. There are more automaker headquarters in southern California than Detroit and with the move of the Los Angeles Auto Show from January when they were a day or two apart) to November, LA could well be America's premier auto show in five years. Advantage: CES

Add-ons. Detroit extends the impact and duration of the auto show with a series of design and insider seminars, charity days, and a 10-day public run. That's good. CES is followed by an insiders' car technology conference, the Consumer Telematics Forum, that's a must-attend for a couple hundred dialed-in people. Both places have casinos though Vegas wins on sheer numbers. Advantage: draw.

Booth models.Nobody at a male-heavy convention ever went to a show to ogle the, er, associates staffing the booth, right? U.S. auto shows have gotten away from the barely dressed look, leaving mostly wholesome looking women and men at most booths, plus evening gown models at the Ferrari and Lamborghini booths. Mainstream CES booths have mainstream models, but it's still the wild west in the North Hall (auto electronics) and the GoDaddy booth. Advantage (of sorts): CES

New cars. No surprise. An auto show has more cars than an electronics show. Advantage: Detroit

New cars that make a difference. General Motors made a big impact by rolling out the hydrogen-powered Cadillac Provoq at CES when chairman Rick Wagoner gave the first-ever CES keynote by an automaker. But Detroit was impressive for the breadth of green cars - hybrids, fuel-cell cars, clean diesels - shown off. In the show that for decades celebrated road-hugging weight, 2008 was an ehiphany. Advantage: Detroit

Future car technology. Detroit allows in automakers, period, plus a handful of suppliers (Alpine, Johnson Controls, Panasonic), while CES is open to everyone. The scope of CES offerings was dazzling, from major players such as Delphi and Visteon, to niche players such as Azentech (in-dash car PC/media player/navigation). GM chairman Wagoner at CES allowed as how electronics more than mechanical componentry is the guiding light for car technology. Exactly so. Advantage: CES

As you might expect, the two shows aren't interchangeable. Detroit for now is the premier place to unveil cars in the U.S., with LA (November) and New York (March) nipping at its heels. CES is the place to see fast-evolving technology that will make the difference in cars two to five years down the road. If you like cars, you need to be in both places, preferably starting in Las Vegas.