When I picture a black cab I don’t picture it actually moving, their traditional role is surely to line the streets or sit in traffic with the engine running, decorating the air with particulates.

Also allow wealthy (usually white male) businessmen to beat the traffic by clogging bus lanes.

There are also a few electric-only buses rolling out. Along with a lot of them being hybrid with auto start-stop now so they aren't polluting while in traffic. Id like to see more of them move to electric only though!