Italian Beauty, with an Edge; Maserati's Quattroporte Sport GT S quickens the pulse.(NEWS)

Byline: J. P. VETTRAINO

Maserati calls its 2009 Quattroporte Sport GT S a "hyper-sport sedan. We call it one of the most emotionally engaging four-door cars money can buy.

Upgrades from the midline Quattroporte S are relatively subtle, but they meld to give the new Sport GT S a singular flair. It's in the look, to be sure, but also in the driving.

All 2009 Quattroportes get a mild face-lift: a new grille, larger headlights trimmed with LED strips, more prominently flared rocker moldings and red-over-white taillight clusters. The Sport GT S adds 20-inch wheels, oval exhaust tips and grille and headlight inserts in dark titanium metallic.

The Sport GT S gets its power from Maserati's larger 4.7-liter V8, developed with Ferrari, rather the 4.2-liter engine in the standard Quattroporte. The net is 433 hp at 7,000 rpm, 8 hp more than the Quattroporte S. Peak torque remains at 362 lb-ft, but there is a bit more available after the peak in the Sport GT S.

The biggest change in the GT S powertrain, according to Maserati test driver Ivan Capelli, lies in the shift-control strategy. The six-speed ZF automatic is programmed for more aggressive gear changes in full auto mode. In manual mode, it won't kick down on its own. It holds a gear indefinitely at the limiter and protects only against overrevving with manual downshifts that are too aggressive.

The Sport GT S's springs are 20 percent stiffer than those in the Quattroporte S, with the same 49/51 front/rear weight distribution. Single-rate shocks replace Maserati's electronically variable Skyhook system. The GT S has the same steering ratio as the S, with alignment geometry altered for sharper turn-in, six-piston brake calipers and slightly wider rear tires (295/30ZR-20s).