The most interesting places are easily accessible by foot and close to each other so you can easily walk from one sight to the other, from one district to the other (or use public transit). You don't really need your car to get around Montreal, you can leave it at a parking lot for the duration of your visit and use the BMW system (bus-metro-walk). By the way, most montrealers don't wait for the green light to cross the street of cross in the middle of the street but that doesn't mean you should do it, it's illegal. Surprisingly, the number of pedestrians hit by cars in Montreal is half of the number of people hit in Toronto where the stereotypical torontonian always wait for the green light. I suppose it's a special Montreal ability that need years of training or the fact that cars can't turn right on red lights.