Waze me
I think about a features for helping to carpooling. All wazers could suscribe to this service.
The car driver submit the number of place, the capacity for luggage etc...
The searcher submit the number of people, the luggage size etc...
If the searcher is one the way of the car driver the service related puts both.
This features can be improve wih a note for the car driver/the searcher. Also with a distance to walk or to drive allowed to go for carpooling, eventually with the possibility to go to the destination with several driver etc...
It could be also possible to have the price of the fuel to do the trip.

Waze Carpool app in going through testing and improvements process.