Two new ideas for improvement
Notification to other drivers of dangerous vehicles (e.g., erratic driver, distracted driver, aggressive driver)
A link to tow services or vehicle assistance along route. Waze could serve as a great assistance if you breakdow and require a tow or vehicle assistance. If you set it up to accept online payment (like Uber) Waze could get a percentage cut of the fees for any tow vehicles dispatched. With the large number of users out there WAze could probably leverage lower fees for their users, provide the tow vehicles exact GPS coordinates of the user's disabled vechicle, allow the user to track the tow truck in route, etc.