I fly into DTW a lot, renting from National/Alamo and have never seen such a thing. If it did exist, it's about 25 minutes to the border, anywhere from 10 minutes to 2 hours at the border, then it seems it's about another 20 minutes to the Windsor Airport. Maybe not the worst thing if your destination is Windsor, but if your destination is on the US side, you will need to drive back, pay the tolls and have another border wait. If this exists, it does not sound worth it. At all.