Yeah, the ability to accelerate from a stop up to 5 to 10mph on electric only really boosts city fuel economy. For a conventional car or bus, this is where they have the absolute worst fuel economy gulping down fuel in 1st or 2nd gear. I'd also suspect that bus drivers taking off from a stop in a regular diesel bus would step on the throttle and cause the engine to run a rich fuel / air mixture. So the benefits accrue here as well in the fuel efficiency and maintenance departments.

Going forward, I'm glad we're seeing explosive growth in all electric buses and cars. They're vastly more efficient and simpler than a hybrid drive train, avoiding the tradeoffs between power and efficiency hybrids had to make. Hybridization was a great technology for its time but it's increasingly being supplanted by full electric architecture.