Like Uber or Lyft, riders can register themselves as ride sharers. Use location-based capabilities to match riders with a car and riders seeking a ride.
Commuters who take their own car to and from Metro can register themselves and the region they are willing to service. As they have breakfast, they go 'on service' as await potential riders that match their departure window. And when they board Metro on their way home, the app calculates their expected arrival at their home station and can offer service for rides home. They automatically get paid for rides provided to and from the Metro. The result is more shared rides to and from Metro stations, and less people driving and parking.