They are making a special version that has a Tesla plug on one side (to plug into the Model S) and a J1772 on the other end where you plug in the public charger. The advantage is that on the car you have the Tesla plug that properly locks and when using this cable you don't also need the adapter. I have not received it yet as he had some problem making it but hopefully it will come soon. In 10 months of ownership on my Model S I have to say I hardly miss it. Quite frankly I only use public charging when it's free and only if it's convenient. Many times I don't even bother. I always have enough range. So I don't think I will use the cable much at all. I will still get it for those road trips or the unexpected situations.
