I've been down that road, and let me tell you, it SUCKS.
A lease is merely a protracted rental of a car. When the lease term is up, you (usually) return the vehicle at the end. You don't own it, so you can't customize it to your tastes, and you have to maintain it.
For personal vehicles, FORGET IT.
Now, if you were leasing a vehicle for a business, e.g., a van for a tradesperson such as a carpenter, plumber, etc., then it would make sense, as you'd reduce your capital costs and also be able to deduct those expenses from your federal and provincial taxes.
EDIT: While it's true a warranty will cover MOST repairs, the lessee (the person leasing the car; the entity which collects the lease payments from you is the lessor) is responsible for maintaining the vehicle. Then there are all sorts of other fees that come into play, such as "excessive wear and tear," and "excess mileage." The latter is important, as you'd lease the car for X miles (okay...kilometers) per year for Y number of years. There would be a fee of so much per unit of distance (miles or kilometers) above that. You might wind up with a rate of C$0.20 per km above 57,936 km (36,000 mi.), to use a random example. Depending how much driving you do, that will get expensive really quickly.
Having a bad taste in my mouth from a prior leasing experience, I'd buy a reliable used car instead, and save up until the new 3- and 5-series models come out. That way, you'd be able to put down a sizeable downpayment on the BMW of your dreams and finance it, meaning you'd own every last nut, bolt and washer when you make that last payment.