DTW to border 30-45 mins
border crossing (depending on time of day) 10-45 mins. Closer to 10-15 if you are nowhere near rush hour.
border to Toronto 3.5 hours

My suggestion, fly into Buffalo, 15-20mins from the border and 1.5 from there to Toronto.
edited to add this:
I take it you have no permanent resident status or canadian citizenship. because if you do, you cannot rent a car in the US and drive into Canada.




[This message has been edited by obiwan (edited 06-21-2002).]