Here in BC, once the tax & transfer form is completed...and that includes the mileage at time of transfer....the owner is no longer permitted to use the plates and registration and insurance as it is not his car any more, nor can you use them. It is called hium doing a "transfer of interest".   Best thing would be to you both go to an Autoplan store and transfer the registration to you and buy a one day temp permit. You will have to  pay provincial taxes and transfer fees at that time I believe.That way you would be covered in case of a crash or interaction with authorities.

Your US dealer plate won't be valid in Canada. You'll have to convince the current owner to leave the BC plate on (and insurance) until you cross the border. The best way would be to trailer  it.

Big AL here, 

Is it a Japspec Mini ?, what actual year ?

Big AL , concerned

Oil is available in Canada. 

Trying to locate Big Al. I have been told he is the man when it comes to bringing a car in from Canada. EPA called and said I'm good with E code on my 3520 and DOT called back and said box 1 on the HS-7. Whee is sending a letter to help with RHD. I fly to Vancouver on the 18th to drive it to Sacramento. I have a dealers lic. and plate. Anything else that might make it smoother. I'm also taking oil. I hear I might need it with a Mini.