Do the cars have an onboard wifi for the server-client communication? Is this API also open to the Internet over the car's cellular connection? (if there is one of course)
All Model S's come with 3 months of cell service and they will be offering data plans shortly. It's running on AT&T, so we should be able to add it to Mobile Share plans (which I plan to do).
/T-Mobile user
They did however say that you'll be able to tether a phone with a data connection to the car via USB to avoid paying a subscription for the car.