Will German rival to London's black cabs catch on?

By Katherine Baldwin

LONDON, Aug 7 (Reuters Life!) - They are as ubiquitous in London as red double-decker buses and as much of a symbol of the British capital as Big Ben, but change is afoot for the black taxi cab.

The classic cab -- viewed by many as a piece of London history -- is facing competition from a larger, more environmentally friendly model made under the Mercedes-Benz marque by German automaker