Carpooling in India is available across the cities in India, including Mumbai. Here you get the option of carpooling on regular basis (that is, daily routes), or casual carpooling (for a specific date).
If you own a car, then you can post about the route you take on the website. And if you don’t have a car, you can get in touch with the car owners. Be it going form Ghatkopar to Lower Parel, or Mumbai to Pune, the website has various routes that are proposed on daily basis.
You can also filter the search as per your requirements: as a passenger, driver or both. This is more like an online group that's great to help co-ordinate and put you in touch with fellow travelers.