I guess this would be a posh version of Lyft or Uber in the States. Download the app onto your phone, order a car, and the rest is easy. They ask for a credit card number and the ride is automatically charged to your card. If you're curious about your driver, a picture and some information appears on the app and you can check him/her out. The passenger is able to determine how much you want to tip the driver (10%, 15%, 20% and I think there is an 'other' option), and you select this on the app. My friend and I got picked up in a fancy white Tesla at Henri-Julien and Beaubien going to YUL. The total was $42 CAD, which included a 15% tip. Very easy app to use and I'll definitely use this service next time I'm in for a visit.