It is now a known fact that the Chinese market has an affinity for long wheelbase vehicles, that is why the Brits from Rolls Royce have complied one again and introduced an Extended Wheelbase version Phantom, this time based on the Series II model, at the 2012 Auto China.
Torsten Muller-Otvos, CEO of Rolls-Royce Motor Cars said that "No other luxury product comes close to Phantom Extended Wheelbase in
staging an object of exquisite beauty, effortless opulence and grand
theatre. I am delighted that our discerning Chinese clients continue to
value Phantom Extended Wheelbase so highly. And with the changes for
Series II I am confident that it will continue to retain its position at
the very pinnacle of the ultra-luxury goods marketplace for many years
to come." 
The new Phantom Extended Wheelbase follows last year’s global debut for Ghost Extended Wheelbase in Shanghai, with power in this case continued to be extracted from the same V12 direct injection engine found in the regular Phantom.
If we are to compare the new LWB Phantom II with the previous PWB Phantom in terms of consumption and emissions, then this latest version is 10 percent more economical and with CO2 levels that have dropped from 388 to 349 g/Km. This was enabled by the new eight-speed automatic transmission and a rear differential which complement the V12 direct injection engine. 

Source: Rolls Royce