The fact is, the most recent of your self, the lower your rate, so you are basically choosing to lock in now while costs are lower and defend against future increases.
However, if a bargain is elsewhere, these guarantees will show themselves that they can be quite beneficial.
Depending on the mileage, age of the car and the conditions of the original warranty, you could end up paying for double coverage.
They know that the driver would have no reason to force virgins problems with it, because the cough for repairs would not be a problem.
They will have your vehicle's paperwork on file and be ready to remind you when maintenance and service must be completed.
Buy a spoiler that is designed for a make and model so as to be assured of the integration of design between the aerodynamics of the car stock and upgrade you want to add.