Tesla Roadster: Proving that the wealthy can have an environmentally sensitive side, too, Tesla managed to sell every $100k-plus Roadster it built. Impractical as anything other than a sunny-day toy, the demise of the Lotus Elise in the U.S. signaled the end of Tesla Roadster production.
Saab (all): Oh, what could have been had Saab not been purchased by GM. The once proud, quirky-but-stout brand from Trollhattan became too integrated with GM over the course of its ownership, ultimately deciding Saab’s fate even before the sale to Spyker. While the Saab 9-5 was a fine car, it felt more like a Buick than a traditional Saab. There’s little hope for a brand revival, but the marque will live on for decades in the hands of faithful and determined owners.
Chevy Aveo: There’s one reason and one reason only to buy a Chevy Aveo: it’s inexpensive, and you need basic transportation. A prime example of why domestic automakers have been losing ground to import brands, the Aveo should have been killed off years ago. It’s replacement, the Sonic, is a superior car in every way.
Chevy Avalanche / Cadillac Escalade EXT: Part truck, part SUV, the Chevy Avalanche helped to create the market for crew-cab pickup trucks. Ironically, the growth in crew-cab sales came at the expense of the Avalanche, which has seen declining sales in recent years. Whether or not the Cadillac Escalade EXT (a badge engineered Avalanche) was a success depends upon your perspective: it never sold in large quantities, but it did out-live the Lincoln Blackwood luxury pickup. Both models are going away in the 2013 model year.
Note: this list originally included the Volvo C70 based on some incorrect information we promulgated (love the word, hate the action implied). The C70's indeed back with us for the 2013 model year--though Volvo confirms the plant that builds it will be shuttered in the near future.