This paper uses a field experiment to learn the pro-social behavior of small and middle distance ride sharing drivers, in collaboration with a Parisian start up. The destination of the passenger is shown on a connected board, and all drivers passing by can pick him up. In the standard setting, lots of drivers refuse to be paid, showing a potential of pro-social behavior among drivers. We tested the payment behavior under several circumstances: short distance versus long distance, normal price versus tripled price, and the possibility to donate the money to charity. Preliminary results show that tripling the price will significantly increase the encashment rate of long distance tickets, but not for short distance. However, adding a donation option will significantly increase the donation rate of short distance tickets, both under normal price and tripled price, but long distance drivers seem not be interested in donating, even under a normal price. We suppose that drivers are more generous for doing a small favor, but when the distance increases, offering a ride share changes from a “favor” to a “service”.