From somebody who spent years in this business in a former life, I'll agree with Meatballs on leasing...

It's easy to not put any money up front except first month and DMV. Let's say you see a lease deal in the newspaper for a new BMW 328i at $399/mo for 36 months. Sounds great until you look at the out of pocket expenses. Usually it's around $2999 down + taxes + DMV. But as Meatballs said, you never want to put money down on a lease, which is very true.

A good rule of thumb if you want to figure out how much a payment will be with nothing down is this:

Figure on $30/month for every $1000 you roll into the payment of a 36 month lease. So that $2999/36 is about 90 bucks a month. So now we're up to $489/month with $0 down and taxes up front. If you want to figure how much it will be per month to roll the taxes into the payment you would multiply the new payment of 489 x 36 x your home sales tax rate. Let's say it's 7%. It comes out to $1232. Divide that by 36, and it's $34/mo. So, to add it all up its $399 + 90 + 34 = $523/month with just the first payment and DMV. It's good to use for a rough estimate and to keep the dealer honest.

Of course it's all dependent on what you can negotiate, but figure for every $1000 a dealer discounts the car, it will translate to $30/month off the payment on a 36 month lease.