Peugeot has just released additional details of their upcoming 508 RHX diesel-hybrid ahead of the Frankfurt Auto Show. The four-wheel -drive flagship model of the 508 range is based on the SW estate. It's powered by a hybrid system that combines a 161hp 2.0-liter diesel engine with a 36hp electric motor. Combined output is rated at 197hp with the power from the diesel engine going to the front wheels and power from the electric motor going to the rear wheels.

This all-wheel-drive diesel-electric technology is called the Hybrid4 drivetrain and is unique to the French automaker (and Citroen). Up to a total of 221 lb-ft of torque is sent to the front wheels and 148 lb-ft goes to the rear, with maximum combined torque measured at 332 lb-ft. The 508 RHX also has four drive modes, consisting of 'Auto,' 'Zero Emissions Vehicle (ZEV,' '4WD,' and 'Sport.' In short journey ZEV mode, it can go entirely on electric power. The engines are mated to a semi-automatic transmission that also has a sequential manual shift option.

Visually speaking, the RHX is more striking than the standard 508 SW. It has an increased ride height, more body-cladding, alloy wheels, and a new front grille and bumper. Also new are those "lion claw" LED daytime running lights. There's also a standard panoramic glass roof along with four-zone climate control, electric driver and passenger seats, laminated side windows, sat-nav, and xenon headlights. Set to go on sale this spring in Europe, final pricing hasn't been announced. More details are expected at Frankfurt next month.