We thought that Acura's new NSX might steal the show -- but Ford had other plans. Source: Honda.

The North American International Auto Show, held every January in Detroit, is one of the world's biggest. It's huge, it's flashy, and it's where the biggest names in the business unveil some of their hottest products in front of the world's automotive media.

I was at the show's media days last week with my Foolish colleague Rex Moore. We brought you video reports from the show floor -- but I also spent a lot of time talking to auto executives and observing what the automakers were emphasizing in their displays. Here are three of the things I learned at last week's show.

Lesson 1: If you want a lot of attention, bring a big surprise.
For months, Honda's (NYSE:HMC) Acura brand had been telling us that its long-awaited new NSX sports car would make its debut in Detroit. 

It did, and it drew a big crowd -- but the crowds around the NSX were nothing like the crowds around the show's biggest surprise, Ford's (NYSE:F) stunning new GT.

A very rare quiet moment around the Ford GT on Ford's stand in Detroit last week. 

The crowds around the Ford GT were three-deep (or deeper) from the moment it was unveiled. Ford only plans to build a few hundred copies, and the price is expected to be sky-high (six figures, I heard, and the first number may not be a "1"), but its mad combination of high technology with just-retro-enough styling -- and the fact that it was a total surprise even to many Ford insiders, developed in a secret room in the basement of Ford's headquarters -- wowed even the jaded auto journalists in the crowd. Ford stole the show, plain and simple.

(I know it doesn't look that crowded in the photo above, but that's because I took that photo at 7:23 on Tuesday morning, while we were waiting on the Ford stand to interview CEO Mark Fields. We'll have that interview for you later this week.)

Lesson 2: How serious is GM about Cadillac? $12 billion serious.
We spent some time talking to the leaders of General Motors' (NYSE:GM) Cadillac brand, which is being separated from GM's corporate structure in an all-out effort to beat the German luxury brands at their own game.

Does that sound crazy? It might, but they're not kidding. New Cadillac president Johan de Nysschen told me that the ATS and CTS sedans are the first moves in what he described as "a deliberate strategy to challenge the German brands in the very segments where they are the strongest," namely luxury sedans -- with more to come.

Cadillac president Johan de Nysschen unveiled the all-new CTS-V in Detroit last week. The new CTS-V, a 640-horsepower super sedan, will go on sale in late summer, he said. Source: General Motors.

De Nysschen laid out his future-product plan for Cadillac late last year, but he had an update for us at the show: GM's board has signed off on the plan, a $12 billion investment in a slew of new products for Cadillac -- including a compact crossover SUV and a new small sedan to challenge Mercedes-Benz's wildly successful CLA.

There's also a brand-new marketing campaign rolling out for Cadillac. Chief marketing officer Uwe Ellinghaus told me that the new campaign will kick off with TV ads starting on Feb. 22. I couldn't get him to drop any details about what we'll see, but he made it clear that the idea of "passion" is at the core of how they plan to present the overhauled Cadillac brand to luxury buyers.

(We'll have the full interviews with de Nysschen and Ellinghaus -- and one with Cadillac chief engineer Dave Leone, who told us about what went into the new CTS-V -- later this week.)

Lesson 3: Fiat Chrysler is striving to make a big impression with Alfa Romeo.
One of the show's strangest events was an elaborate Fiat Chrysler (NYSE:FCAU) presentation that featured several achingly beautiful (and achingly valuable) vintage Alfa Romeo sports and race cars -- but no significant new-model debut.

FCA executive Reid Bigland presented the new Alfa Romeo 4C Spider in Detroit last week. Source: Fiat Chrysler Automobiles.

Alfa's U.S. chief Reid Bigland did unveil a new open-top version of the 4C sports car, currently the only Alfa Romeo model available in the U.S. But what made the event strange was the obvious amount of effort put into it and its early-morning time slot -- both of which seemed to promise big news that Bigland didn't deliver.

It's known that FCA is making a big investment in a slew of new Alfa Romeos, which are being developed in a "skunk works" in Italy. It's also known that the first of those new models is likely to be unveiled sometime this year. Bigland reiterated all of that, and the fact that this event happened at all emphasized the importance of the Alfa revival to FCA. But aside from the classic cars, there was really nothing to see here.