Where I used to live most taxis were Priuses. On one occasion, the driver was explaining most were converted to LPG and they achieved pretty amazing economy. Not entirely sure I believed the numbers.
In Edinburgh, at Waverley, there is a down ramp for taxis. Which means that instead of having to start the engine every few minutes to move towards the pick-up point, they could just roll. (Probably illegal - especially with servo-assisted brakes.) Much, much cleaner than starting engines repeatedly. Anywhere that very short moves, and waits, occur, hybrid can justify itself over pure ICE. I really don't understand why we don't see almost all Post Office vans in hybrid form. Certainly round here, they drive up, stop, switch off, deliver to one or two houses. Jump back in, start and drive for a few more yards. Often a nice belch of diesel smoke as they go. (Some posties walk much further than others. And I do understand where there is significant weight to carry.)