The idea here is that your lease is a sunk cost, in that you’re buying it with or without a MSD factor.
Here’s how it works out as an “investment” in that scenario. Really I use “investment” in quote for a reason, as it’s not really an investment. It’s just a reduction in costs of your lease, but if you were to assume you were leasing regardless, it’s a great return.
BMW lease, assume $50k car for 36mo and 60% residual for easier math.
Original MF of .00131
Max MSD MF of .00082
Original MF lease finance charge = $3,772.80 = (50000+50000x0.6)x0.00131x36
Max MSD MF lease finance charge = $2,361.60 = (50000+50000x0.6)x0.00082x36
Monthly payment for this lease would be $621.16, so a $4,550 deposit for max MSD.
This results as if you were to include a MSD, you can reduce your payment (total lease cost) by $1,411.2 and thus a “return” of 31% in the 36 months on your “investment” of a MSD.