Kafka, I'm not sure which part of Canada you're in, but I know all the BMW Driver's schools in the North Eastern part of the US do not allow convertibles. However, I do not know the rules for the Canadian driver's schools. You should contact your local chapter of the BMW Club of Canada http://www.bmwclub.ca/
and then click on your closest chapter on the left side. They will be able to tell you their rules before you buy the car. Good Luck.