eCall isn't mandatory until April 2018, however, if you are looking at vehicles with a 6 month frikkin lead time and maybe a shelf life at the dealership, I'd expect it to happen sometime around now.
Can't say its a feature I'd go out of my way to acquire... I suspect in those places where your accident isn't spotted by someone else then its somewhere with bugger all cell reception for the thing to call home anyway.
I'd probably also doubt if Her Maj's plod have the call handling equipment to receive the location data that it sends either!