Buy vs. Lease vs. Keep Car
Net cost of each option over the same number of years: what you pay out minus what the car is worth at the end.
How this is calculated
What you pay out covers loan or lease payments, cash paid up front, sales tax, insurance, maintenance, fuel and fees. What the car is worth at the end is its depreciated value minus any loan still owed on it. A lease ends with no car, so nothing comes off its cost.
Leases renew back to back for the whole period, each with a new drive-off cost and a disposition fee when it ends. Monthly-equivalent is net cost divided by the number of months.