Leasing is all about the residual and the lease cash rebate on the front end.
55% is typical for a 3 yr lease of a current year car. In this guy's case, his residual for a 2018 is 47% so I asked if a lease payment on a 2019 had a higher residual and a lower payment because of that. BTW, $600 a month with $2k down is not a great deal on a leftover Stinger, even a GT2.
OTOH, Kia is putting lease cash discounts of around $8k that can be used to lower the cost of the car if you buy out the lease. in my case, my 2018 GT1 sticker $49k will cost me $40,500 OTD including tax tags etc when I buy it out next month. That is a similar deal to what he is getting on the 2018 GT2, but I think in his case he is looking at another $6k in "rent charges" or "imputed interest" if he takes the lease to term. BTW, the interest rate in that lease is 5.7%. Mine was 4.7%. I'd buy that lease out if I can get a 4% or lower car loan to replace it.