There are two essential technical cornerstones for deployment of the connected vehicle.

Interoperability between different  vehicle manufactures, different vehicle types, aftermarket devices (if realized) and the infrastructure

and

Secure communications

Reliance on off-board information is new to the automotive realm, where to date the only real vehicle-to-roadway and vehicle-to-vehicle interfaces (not counting the driver) have been tire-to-pavement and metal-to-metal.

Stakes for roadway operators and vehicle mfrs using communications for safety are considerably higher than they are in the traditional communications realm of consumer electronics.