Okay, now I'll do the incredibly brief leasing crash-course. I'm always amazed at the misconceptions surrounding leases and how some people think they're instruments of Satan.
First of all, a lease isn't paying for the car. It's paying for the value that the car loses during the time you have it. Say, for example, that the car is worth $40k when you acquire it. If it's worth $25k at the end of your lease term, your total payments would equal the $15k difference plus interest. It's basically a souped-up rental.
As far as losing your down payment, that's total crap in every way. What happens is that the at-fault person's insurance pays for the value of the vehicle, but to the leasing company, it's identical to an early lease termination. Often, people still owe more on the lease than the insurance company pays, leading to that misconception. This is why GAP insurance was created. It covers the difference, letting you walk away with no further burden on a vehicle that you no longer have. It's inexpensive, and most leases actually require that you have it.
As far as saving more money by not having a down payment, again, crap. Let's think about basic math. If you owe someone an amount, how is it even remotely possible to owe them less by paying it over time (with interest), than it is to pay it all upfront? Srs148, what they did with you was to play with your interest rate and or mileage factors to give you that impression.
I can go on forever, but here's the basic advice: Monthly payment isn't the most important thing with a lease. Many people get caught up in what the payment is and make poor decisions by looking at the tree instead of the forest. Your most important factors are vehicle selling price, interest/miles, and residual. Miles aren't really that important if you work the rest right, because you can often sell or trade the vehicle at the end for more than the lease payoff, making mileage completely irrelevant. Make sure the selling price is what you'd be willing to pay for it if you were doing a purchase. Next, make sure the interest rate is good. It's often not, because leasing has gone up in popularity lately because of the economy and the public perception that it's the only affordable way to have a new car. The residual is equally important, and is figured based on projected resale value of the car at the end of the lease term. All of these are things to be considered. Let me know if you have any practical questions.