Startup Idea : Car-sharing Realtime Mobile App

I would like to have mobile app which will help me to fill my car by people (co-riders) if I go somewhere. We can share costs, be eco and meet new people. There are car-sharing and ride-sharing services available but none of them is real-time. On the other side - if you need to get somewhere e.g. commuting to work why not to jump in someone's car, share costs, get comfortable ride and be faster compared to buses or trains. App could work globally and provide only local based search result of ride seekers and drivers. How do you like it? Contact me on @kotyzap if you want more info. Have a great day and greetings from beautiful Czech Republic.