I once managed one of the largest lease fleets in the U.S. for a major auto manufacturer, and would consider myself a auto leasing expert. I could write you a book on this subject, but I'll keep it as short as possible.
Leasing is essentially balloon financing--small monthly payments with a large payment at the end. The lease payoffs are slow to come down, and Gap Insurance is to payoff the car if it's a total wreck and the insurance company will not pay it in full.
Leasing is not for everyone. It's best for relatively low mileage users that like to keep a late model, trouble free vehicle. When the lease is up, turn it in and get another. If you're always going to have a car payment, go for the payment that's cheaper. And in many states, sales taxes are kinder being paid on a monthly payment rather than on the full price of a vehicle (on a purchase.)
Most dealerships are "selling" retail leasing as an alternative to purchasing--and the auto manufacturers "buy" the lease from them and do all administration. The manufacturer's finance company is responsible for the lease end value, and it's out of their pocket if the car's not worth the projected value in 24-30-36 months. Auto manufacturers will often subvene the interest rate or give sales incentives on retail leasing--sweetening the deal.
Wholesale leasing is when the dealer has his own in house leasing company. They're usually doing fleet leasing and not dealing with individuals. The dealer will also finance the cars with the manufacturer's financing arm usually and might pay 1.5% amortization per month plus a balloon payment in 24 or 36 months + interest on the declining balance. Since the dealer's responsible for the lease end value, dealers will be conservative on LEV. Utrect was quoted this kind of lease, and it is not for an individual. The dealer's profits are when the car's sold at the lease end.
Please just realize that most lease payments are being quoted on the list price of the vehicle. Lease customers are not negotiating on price, but on monthly payment. When you're quoted a lease payment, begin negotiating for a lower payment.
Some vehicles have a wide MSRP vs. cost spread, and the dealer has room to negotiate payments. Some cars like Honda's and certain Toyotas have a high resale value and that can attribute to very low lease payments. Just don't allow the dealer to sell you any other service--GAP insurance, etc.