Old-world charm, resolute styling and blue-blooded buyers may not be the first things one mentally associates with hybrid cars, but Rolls-Royce thinks the combination makes perfect sense.

Instantaneous torque, quiet operation and excellent fuel-economy all work in favor of a gasoline-electric Rolls, so it comes as little surprise that the automaker is working on a hybrid version of its latest luxury sedan, the 2010 Rolls-Royce Ghost.

The gasoline-electric Ghost will reportedly borrow hybrid technology from BMW’s ActiveHybrid 7. It’s no coincidence that the two models already share much in common, including the same rear-wheel drive platform.

The new hybrid powertrain will combine the Ghost’s 6.6-liter twin-turbocharged V-12 engine with an electric motor in a ‘mild’ hybrid configuration. This means that the Ghost hybrid won’t be able to drive on electric propulsion alone. An autonomous engine stop-start system will also feature to help improve fuel economy further.

The electric motor, which will be rated at 27 horsepower and 155 pound-feet of torque, will be mated to the Ghost’s 8-speed ZF automatic transmission and run on a small lithium-ion battery pack mounted in the trunk. Brake energy recovery technology will be used to top these up.

The end result should be an improvement in fuel economy of about 15% but the biggest benefit will come from the extra torque sourced from the electric motor, especially during off-the-line acceleration.

No word on any release date but expect its launch to be several years away at the least. Interestingly, Rolls-Royce CEO Tom Purves has already professed his love of all-electric powertrains, revealing only last month that he would love to see such an option available in a car like the Phantom.