With no end in sight to the popularity of sport utility vehicles, General Motors is planning to roll out at least four new luxury SUVs over the next year or so, including two Cadillacs, a Buick and a Hummer, according to Reuters. "The luxury SUV market has gone from zero to three-quarters of a million units a year; it's exploding," said George Magliano, director of automotive industry research for North and South America with DRI-WEFA. The forthcoming SUVs play up GM's strengths in the truck market, key to the automaker's strong earnings growth this year, according to industry analysts.