Billy is considering buying a 2017 Tesla Model S costing $75,000 and finds that the retaining values of the vehicle over the next eight years are as follows:
Percent of the total value retained after 48 months: 54%
Percent of the total value retained after 96 months: 23%
If his interest rate is 5% compounded annually, what is the ownership cost of the vehicle over 4 years? 8 years?