Provisioning for a hypothetical electric car
See SAE J1772


  In the 2009 standard, two charging levels are defined.

            Voltage  Phase          Peak current
AC Level 1  120 V    Single phase   16 A
AC Level 2  240 V    Split phase    32 A (2001)
                                    80 A (2009)



Nissan say


  Most Nissan LEAF owners recharge their cars at home. The 6.6kW charger option lets you charge your Nissan LEAF at home in just 4 hours using a 32A Home Charging Unit


For that option you'd need a dedicated 240 volt 32 amp circuit.

Until you actually have an electric car it may be best to leave that circuit terminated in a junction box of some sort and leave the fitting of a charging-unit until later. You probably shouldn't fit a regular 240 V 32A outlet because the J1772 system requires some intelligence be built in to the supply side (the charging unit).

In some countries the government will pay you up to $1600 to have a charging point fitted in your garage. If you live in such a country, it might be worthwhile taking advantage of such offers whilst they are still available.