Because you can't catch a whiff of that new car smell through your iPhone.
Photos can't re-create the smell of leather seats or the smooth feel of a hood. At this year's North American International Auto Show in Detroit, which opens to the public Jan. 19, visitors can see 500 cars and trucks spread over 18 carpeted acres. At least 800,000 people are expected to take in all the shiny models, amid the bright lights and thumping mood music.
The biggest draw will be the first new Corvette in nine years. Technology lovers can see an experimental concept from electric carmaker Tesla and a diesel version of the Jeep Grand Cherokee. Young buyers can check out a small SUV concept from Honda. Big spenders -- and big dreamers -- can take a gander at the new Bentley convertible.
But for all the gleaming metal, most models won't be new to fans. Corvette lovers have been salivating over drawings posted on the Web. Spy cameras snapped an Acura MDX last fall, months before its official debut in Detroit. Mercedes has already released photos of its E-Class coupe and convertible.
But even with all those spoilers, visitors keep flocking to Detroit and other auto shows. They want to touch the cars, check out the trunk space or just hop in.
"You can't do enough on a screen. You can't crawl inside and get a feel for it," says Rod Alberts, a 23-year veteran of the Detroit show who is now its executive director.
Detroit is one of 65 shows that will be held in the U.S. this year, from a tiny one in Toledo to New York and Chicago gatherings that attract more than 1 million visitors each year. Detroit has been holding an auto show almost continuously since the early 1900s, when local dealers lined up a handful of cars alongside fishing and hunting gear.
More than half of visitors at the Detroit show are shopping for a new car, according to informal polls. And with car sales stronger than they've been in five years, attendance at NAIAS and other shows could be higher in 2013, after slipping during the recession. Car sales rose 13 percent to 14.5 million last year and could reach 15 million in 2013.
The auto show is the ideal venue for shoppers because they can browse without being pestered by salespeople, says Michelle Krebs, a senior analyst with car buying site Edmunds.com.
"It's like the circus. It's the only place you can see it under one roof," she says.
It's also a circus for car companies. Literally. Infiniti will use performers from Cirque du Soleil to introduce its new small car in Detroit.
"Auto shows are one of the rare moments that the brand can meet the customer, shake their hand, look them in the eye and say, 'This is who we are,'" says Jim Farley, Ford's global marketing director.
Car companies had to cut back on their displays during the downturn. Most are no longer doing the kinds of expensive stunts they did at the Detroit show before the sobering recession, which forced them to close plants and lay off thousands of workers. In 1992, then-Chrysler chief Bob Lutz drove the new Jeep Grand Cherokee through a plate glass window. This year, Lutz will be talking to a holographic image of Thomas Edison at the display of electric-truck maker Via Motors.
And the element of surprise is gone. Icons like the Ford Mustang and Dodge Viper were seen for the first time when sheets were pulled off of them in Detroit. As recently as 2000, there were audible gasps when General Motors revealed the ungainly Pontiac Aztek.
"There isn't going to be that sort of shock and awe that you had at earlier shows," says Justin Hyde, senior editor of the Yahoo Autos' Motoramic blog.
Bloggers are already abuzz about whether a new Ferrari supercar will appear next year in Detroit.
Still, Hyde says, the show is the best place to get a lot of information about cars in a global market that's become huge and fractured. More than 6,000 journalists from 70 countries will attend two days of media previews starting on Monday, giving the show a reach far beyond Detroit. That's up from just 850 journalists 25 years ago.
Nissan is one of several brands that pulled out of the Detroit show in recent years, only to return when they realized its impact. This year, Nissan is going all out, even appealing to the sense of smell in its display. It plans to pump a green tea-like fragrance into its Detroit exhibit.
The idea? To put visitors at ease. And maybe get them to part with a little green of their own.