Google Maps already provides this but with public transit -- real-time notifications of when your bus/train is departing for going home/work. Granted that you

Google Maps already provides this but with public transit -- real-time notifications of when your bus/train is departing for going home/work. Granted that you have to explicitly set home/work addresses and what your regular departure time ranges (eg: go to work between 7-8am and go home between 5-6pm). Tbh this sounds exactly like what you're describing but with public car-pooling substituted for public transit.