I understand that they are. And the cars (and engines) are much older than would be preferable because updating the regulations to mandate newer vehicles gets a

I understand that they are. And the cars (and engines) are much older than would be preferable because updating the regulations to mandate newer vehicles gets a lot of push back. The vehicles are privately owned, the drivers do not want to fork out for a new one. Black cabs are much more expensive than prius because of the limited number of approved models and manufacturers. Source: friends who work air quality policy for tfl/city hall