The Big SUV's death rattle

    As manufacturers discontinue old-style SUVs, they're moving their nameplates to crossovers. The next Chevy Tahoe is going to be built on the Traverse crossover platform, not the Silverado truck platform. And the 2011 Ford Explorer moves from the Ranger truck platform to the Taurus car platform. Equipped with Ford's (F, Fortune 500) turbocharged four-cylinder engine, it is expected to get 30% better fuel economy -- 19 miles per gallon city versus 13 mpg for the V-6 equipped 2010 model.

    At its best, the auto industry is Darwinistic, with the new and improved driving out the old and outmoded, and the change from SUVs to crossovers is a prime example of how it evolves.

    The crossover offers improved flexibility and utility without the penalties of fuel economy and comfort. It will be interesting to see how it mutates. The convertible Murano may be only the first step.