Manicure:
I lived in Montreal until 1997. I pretty much went to the Grand Prix of Montreal every year until then, starting in the mid-late 1980s. Never heard of it, either in the regular press, or the underground press (there are a couple of "free" papers in English that cover the stuff that the mainstream Montreal Gazette (and at one time the Montreal Star) don't). There was no mention in those either. It is possible that this may be going on, but highly doubtful. This seems to be very close to the borderline of slavery. Montreal cops are pretty cool about a lot of things related to the sex trade, but this wouldn't get by, I don't think.
On the other hand, there are a LOT of exotics running around downtown Montreal in the week or two leading up to the Grand Prix. Lamborghinis, Ferraris, Maseratis, Porsches and Jaguars are a given. But at times, you might end up seeing something like an Aston Martin Bulldog, Volante, Jaguar XJ220, or the odd Pagani, Vector, or McLaren F1. There is a lot of money involved when cars like that are around. A lot of the cars come in for the "show", which is a display of exotics on Crescent Street during the week of the race. This may have changed some when they moved the US Grand Prix closer to the Montreal race.
Usually, after the race, the muscle cars show up (Chevelle SS454s, Big Block Novas and Dodfe Darts, Boss 429 and 302 Mustangs, a few Dodge/Plymouth Hemis (original Hemi) are on Crescent Street.
Kinman