In building my garage, I took a look at putting in a power plug for future electric vehicles, since it is easier to do it before the walls are closed up. A standard plug will get you under 10km/hour of charge, so not all that useful. The next upgrade is a 50A circuit, which is good for about 32km/hour, so a full night will get you near a full charge. This looks like the most reasonable option. A high amp charger will do about 50km/hour, requiring a 100A breaker.
Now, I just upgraded my service to 200A, with 100A for the house, leaving 100A for the garage. Most info I read when building the garage was that typically people run 40A or 60A panels. I've got to wonder how many people will be equipped to handle electric cars when they become more common? Adding a 50A circuit isn't necessarily a cheap easy upgrade, and anything less than that isn't going to be very useful.
https://www.tesla.com/en_CA/support/...dard-equipment