As your vehicle accrues age and miles, the price for an extended auto warranty will rise as do the repair costs that you would experience for an older, out-of-warranty vehicle.
You are only buying total mileage coverage, not addition of mileage to your current total. Capitalizing now on your vehicle's newness and low mileage is the most logical approach as you plan for inevitable future repair costs.
An extended auto warranty will provide you with peace-of-mind protection regarding such expenses. Some are transferable, allowing for increased vehicle resale value.