The new Chevrolet Camaro makes the Chevy Corvette look bad. At least in sales-column tallies.

Corvette sales plunged last year. OK, virtually all vehicle sales dived into the rocks. The industry was down 21.2%, according to Ward’s data. But Corvette deliveries dropped 48.3%, from 26,971 units in 2008 to 13,934 in 2009. You must go back to 1961 for a worse Corvette sales year.

Last year was hard on the luxury sports car segment in general. Audi TT sales were off 56.9%, Mercedes-Benz SLK sales down 48.1%. But those cars didn’t have a new baby brother named Camaro getting all sorts of attention – and sales. (Left photo: Chevrolet Corvette. Right: Chevy Camaro gets pampered at Detroit auto show.)

The Camaro looks like a sports car but officially falls into a vehicle segment Ward’s calls “middle specialty.” The first model debuted in 1966 to vie with the Ford Mustang. The Mustang proved more popular year after year. General Motors pulled the plug on the Camaro in 2002.

An all-new and vastly improved version reappeared last year to high acclaim because of its good looks, refined driving traits and impressive power. Engine choices include a potent V-8 and a V-6 that is more fuel efficient but still flexes plenty of muscle.

GM delivered 61,648 Camaros in 2009, but not for the full year, because the car only went on sale in the spring. Ford sold 66,623 Mustangs from January to December.

Perhaps GM should worry less about the Camaro outselling the Mustang and more about it biting into its sibling rival, the Corvette. Website metrics show the Camaro is the Corvette’s most cross-shopped competitor.

During the Camaro’s first go-around, it was dubbed the poor man’s Corvette. The new version is moderately priced: $22,995 for starters and past $30,000 if you opt for the V-8. But the Camaro still costs much less than the Corvette, which starts at $48,900 and reaches $106,880 for the ZR1.

Fact is, the Corvette is an incredible car. And a relative bargain. It’s comparable in driving performance to European sports cars that cost twice as much. The Corvette personifies GM’s brain trust, and plenty of that remains despite hard times.

True lovers of the Corvette will settle for nothing else, no matter how much noise a baby brother makes.

Nor do ultra-orthodox followers of the Corvette brand want to see spin-offs to boost sales.

A few years back, GM toyed with offering the choice of a V-6 in a Corvette, on the premise that it would lure potential buyers, mainly women, who like how the car looks, yet aren’t big V-8 fans. But the V-6 Corvette plan died the death in Detroit.

Now, retiring GM Vice Chairman Bob Lutz hints the auto maker might come out with a 4-door Corvette, although it is not clear if such a high-end Chevrolet sedan would actually be called a Corvette.

In 1980, GM planned on introducing a 4-door “Corvette America.” A contractor built a prototype and five production models. That’s as far as it got.

A 4-door Corvette could draw shoppers who want an iconic sports car with more than two seats. But it would offend purists. A Ward’s colleague, Tom Murphy, told me the idea of a 4-door Corvette “turns my stomach.”

I decided not to ask him what he thought about the notion of a Corvette SUV.