Hybrid plug-in technology development in public transit

I have been studying the public transit bus issue for years. The all-electric buses are designed with low-power; insufficient range under severe mountain and winter conditions; need for charging at stations during each operation day. The all-diesel buses have a high failure rate, with particulate filter requirements causing downed buses to be one-sixth of operating buses on any given day. I envision a bus model that will have a battery pack over-night charging range of 100 to 200 miles. However, I want a bus with a motor as powerful as a 400 HP diesel engine; with a cabin heating system that can keep a bus warm and defrosted in -20 F weather with 60 passengers adding water vapor to the air; and a range extender gasoline generator that will run to add charge to the battery pack constantly throughout the day to push range out to 300 miles. The biggest problem is that existing bus manufacturers are designing buses for big cities with emission limits, trying to produce zero-tailpipe instead of trying to create more reliable, longer-distance, powerful, lower-emission vehicles. I would love to hear from mechanical engineers about potential solutions to the issue.