Don't know but you can probably start at http://www.tc.gc.ca/eng/roadsafety/safevehicles-importation-index-443.htm.
The irony is that the Rav4 EV is supposedly built in Canada (http://pressroom.toyota.com/releases/toyota+tesla+build+rav4+ev+woodstock+ontario.htm).
I think the other issue to worry about is service and the US warranty (e.g. whether you have to jump thru hoops if you have warranty and/or recall work done in Canada).