I would just offer to not fixate so much on totaling a car. Sometimes these things become self-fulfilling. I’ve totaled two cars and both were over ten years old so not a big thing. One was repaired though and back on the road.
Either way, unless you pay cash, if you wreck the car, the bank is going to want what you owe them. The rest you can use to replace the car. On a lease, they are going to expect you to complete the lease and replace the car, just like a rental car where they expect you to pay for lost sales.
You’re not going to get anything back other than what the insurance policy says you will get “back,” which is nothing. GAP will pay the difference between what you owe and what the car is currently worth. Then your regular insurance (or the other guy’s, depending on whose fault the wreck was) pays you what the car is worth, minus deductible.
So if you put $50k down and wreck it on the way home from the dealership, you’re out $50k unless the value of the car is high enough for you to get it back.
The only exception is if you bought Gap Insurance while while it wouldn’t cover your downpayment, it would cover the difference between the Market Value and the remaining balance of your loan or lease obligation.