Sorry if this has been asked and answered, I searched and couldn't find it (please let me know where if so). I bought my Model S in 2013 before there was consumer leasing (business leasing probably started right around when I bought it). I am planning on leasing a new one. I have been building and pricing out my new Model S in the design studio every few months, and each time the monthly lease payment it shows is less than before. What are the monthly payments it shows based on? Prime rate hasn't gone down, it was flat for an eternity and then raised a fraction of a percent, so that doesn't explain why the monthly lease payment shown by Tesla has steadily gone down (the cash price of the car has remained the same). Also I like the payment rate I see now a lot, but I suspect even if I ordered and put down a deposit today I wouldn't get that payment. When is the monthly payment amount locked in, when the deposit is made, or at delivery, or is there some other time when the lease is finalized and terms become firm? Thanks for any info on these questions.