Launched in 1998 as the last and most expensive iteration of the well-regarded Turbo R line, the Turbo RT Mulliner was available only via special order, built to individual specification and outfitted with the very best Bentley offered.

These cars were identifiable by more aerodynamic and prominent bumpers, vented bodywork, flared wheel arches, and larger 18-inch alloy wheels clad in lower-profile tires.

Under the hood, a revised turbocharger, a remapped Zytek engine management system, and a freer-flowing intake brought total claimed output of the 6.75-liter V-8 engine to 420 horsepower and 634 pound-feet of torque.

Despite the car’s considerable size and mass, performance was impressive, with the kind of effortless acceleration Bentley is famous for.

Among the rarest Bentleys of its generation, only 56 Turbo RT Mulliner examples were produced, all but one of which are believed to be 1998 models.

Based on its chassis number, the example offered here appears to be the sole 1999 mod...