Just a month after rolling out its lease-to-own financing program, and generating more than its share of bad reviews in the process, Tesla (NASDAQ:TSLA) says it's amending the program. It will now guarantee those who lease a Model S will be able to return the car after three years with a residual value of at least 50% of its sticker price, versus the 43% the company announced last month, and is extending the length of the lease-to-own contracts to 72 months from 63. (Conference Call Webcast).