Rolls-Royce abandoned the 102EX battery-car concept when potential buyers turned thumbs-down.

If you think “green” when someone mentions Rolls-Royce, you’re probably thinking about the cost of the maker’s big sedans, coupes and convertibles which can push you up and above the $500,000 in a hurry. But Rolls could add a new meaning if it goes ahead with plans to add a plug-in hybrid to its line-up.

Don’t be surprised to see one in the near future, CEO Torsten Muller-Otvos reveals – though not necessarily because Rolls elite buyers are demanding one.

“It will be essential in two years, maybe not from customer demand but through legal regulation on emissions,” Muller-Otvos told British publication Auto Express during an interview at the Geneva Motor Show.

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Rolls-Royce is facing some serious regulatory challenges in key markets including the U.S., Europe and Japan.  New CO2 emissions and fuel economy standards will be tough to meet with vehicles like the flagship Phantom, which delivers a mere 11 miles per gallon around town and 19 on the highway. The smaller Rolls Ghost does only slightly better, at 13 and 21.  Even offsetting those numbers with the higher fuel economy of sibling BMW and Mini products likely won’t go far enough.

The British-based maker has been pondering its options for several years now, and previously explored the idea of going pure battery-electric with the 100EX and 102EX Phantom concepts.  But the reaction was far from overwhelming.

“We showed that car to around 100 customers around world, and the reaction we got was ambivalent,” said Rolls’ CEO. “A Rolls-Royce cannot come with any kind of compromise, and both the recharging times and the range were not acceptable for our buyers – but with hybrid technology that is no longer a problem.”

But while the idea of a 100% electric just didn’t fit the brand, a plug-in apparently could make more sense.  After all, even with a dead battery, the vehicle would continue to run on gasoline power.  And, if anything, other luxury makers, such as Porsche are demonstrating that designed the right way, hybrids actually can improve a vehicle’s performance.

Arch-rival Bentley, meanwhile, is turning to the rest of the Volkswagen Automotive Group for help in developing the plug-in version of its planned sport-utility vehicle.

(VW boosts investment in green technology. Click Here for the full story.)

In fact, Rolls is turning to its own parent, noting that without the help of BMW, the British carmaker “would probably not have survived.”  BMW already has an array of conventional hybrids in its line-up, and is developing a plug-in version of its popular X5 Sport Activity Vehicle, the eDrive.

That system uses a turbocharged four-cylinder engine paired with an electric motor.  Whether it would deliver enough power to drive a car as big as the Phantom, or even the Ghost, remains to be seen.  It is also quite possible the system has enough flexibility to use a more powerful six or even eight-cylinder gas engine as its primary drive.

Going with a plug-in could deliver another plus for Rolls-Royce buyers.  A number of cities around the world are taking steps to address not only endemic pollution problems but also worsening traffic congestion.  London has had a daily congestion fee in place for the last decade. Beijing and a number of other Chinese cities are now limiting the number of new vehicles that can be registered each month. And some cities are considering outright bans on vehicles powered by internal combustion.

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But many of these restrictions are waived for vehicles operating in zero-emission mode.  And that, for the sort of customer who chooses a Rolls-Royce, would only enhance the concept of a no-compromise vehicle.