Actually it’s better than Yellow, naming-wise. Usually, we would advise against using the word “Green” as a modifier to a business name as a way of conveying “echo-friendly”. It’s done so much that Green noise becomes White noise. It’s hack naming, and only appropriate for hacks, hence Green Cab of San Francisco.
It’s the perfect name for a cab company comprised entirely of hybrid vehicles’, and it also leverages the until now untouchably iconic Yellow Cab brand against itself. Nice. And success is guaranteed by the fact that by simply calling Green Cab instead of Yellow, the customer feels like they have done something honorable.