Available this spring, the production versions of the all-new 2006 M35 and M45 sedans are powered by a 3.5-liter V-6 and 4.5-liter V-8, respectively. The V-6 is good for 280 hp and 270 lb-ft and the V-8 will produce 335 hp and 340 lb-ft. Both powerplants are mated to a five-speed manu-matic transmission. We've driven the cars, and they're quite good. And though the driving dynamics and feedback aren't as outstanding or communicative as BMW's, they lend credence to the lofty aspirations Infiniti has set for itself and make the M a true contender for the mid-size luxury-sedan crown.

The dynamically improved M is built on Nissan's successful FM (front-midship) platform, which already underpins the Nissan 350Z and the Infiniti G35, FX35, and FX45. Sport models feature what Infiniti has dubbed Rear Active Steer, which adjusts the rear suspension based upon driver steering input and vehicle speed, as well as nineteen-inch wheels and stiffer springs and dampers. An all-wheel-drive system is only available with the V-6 M35.

The exterior of the new M is more appealing than the outgoing model, but still fairly bland. Inside, leather upholstery is joined by aluminum trim on Sport models and rosewood on the rest. Options include intelligent cruise control, Bose sound, DVD entertainment, and a lane departure warning system, among others. In all, five models will be offered: M35, M35 Sport, M35x AWD, M45, and M45 Sport. Prices are set to begin at $39,900 for the M35 and $46,750 for the M45.