Startup Idea : Share your car

how many times do you see a car of 4 or 5 person... and there is only the driver? This is a waste! first of all you are wasting gasoil, because if the car was empty, you could share costs. Is also a waste of time (because instead of being one car for 5 person, there will be five cars for 5 person, it would be only the driver) we can conclude that traffic would be more intense. In addition you are loosing the opportunity to meet people of your city, that maybe work near you, or will eat in the same restaurant that you planned for this night! Last but not least, sharing car will help to polute less our earth. This project is a kind of Uber but mixed with bla-bla car.