For that short a visit you will be wasting 4 days of your valuable vacation time (14-16 days) on the road (unless you are a Cannonball driver
) plus you need to factor in 2 nights paying for a hotel and the wear and tear from driving your M3 approximately 1400 miles each way.
You didn't say what part of Florida you are heading towards but if it is in the Miami - Ft. Lauderdale area you should be able to find plenty of nonstop flights from YYZ - FLL/ MIA in the $400-$600 range. Usually there are more N/S flights and better deals going to FLL.
If you want to drive a BMW while in Florida, SIXT rents them at both airports and many models are priced under $100 a day. If money is an issue, you will find plenty of less expensive rental options for other car brands and rental companies if you do your research.
To me, maximizing my vacation time is a quality of life issue and I would never consider driving based on such a short trip.
