MONTVALE, NJ — Mercedes-Benz will launch a diesel M-class SUV by 2006, says Paul Halata, CEO of Mercedes-Benz USA LLC. The M-class diesel will use Mercedes' new 3.0-liter V-6 engine, according to Automotive News. A nameplate hasn't been decided. The second-generation M class was unveiled on January 9. It goes on sale in the United States in April. Because of tougher emissions requirements and fuel quality, the M-class diesel will only be sold in 45 states, Halata says. This means it won't be available in New York and California, he adds, much to the chagrin of dealers in both cities who they can't sell diesels.