There are already a few common standards (at least here in Europe.) For public charging station almost every manufacturer uses the TYPE2 (MENNEKES) plug, the a

There are already a few common standards (at least here in Europe.) For public charging station almost every manufacturer uses the TYPE2 (MENNEKES) plug, the actual charger is built into the car. For fast-charging there's the CHADEMO standard (japanese) which a lot of electric cars use and the newer 'European' Combo-plug (an extension to the TYPE2 plug) that is currently in-use by the BMW i3. In The Netherlands (where I live) a company called FastNed is building a fast-charging network on the highways, they offer TYPE2 (for cars not having fast-charging support,) COMBO, and CHADEMO and usually also have a conversion plug for Tesla cars so you can also charge them there. I hope part of this subsidy allows companies like them to get stations along the German highways as well.