Tesla Model S configurator small improvement

Looking closely at the Tesla Model S configurator, I noticed that the options show a price only when the "Cash" method has been selected.  

Why not also show a price per month, cost per option when the "Lease" or "Loan" options have been selected?  That is not a complex calculation to make and would help people select the options that would satisfy their budget without having to  check and uncheck options to see their impact on the monthly payment.