"Do I have to buy a service or maintenance contract at the time of vehicle purchase?
It depends. Vehicle service contracts may be purchased at any time while the manufacturer'* warranty is still in effect. After the warranty has expired, a vehicle service contract may be purchased only at the time of vehicle purchase. Vehicle maintenance contracts can be purchased at any time."
And after having been in the service business for a long time, there IS NOT a service contract, factory OR aftermarket, that is "bumper to bumper". The GMPP is very good, but here is a list of exclusions.
* Maintenance services and parts (refer to coverage agreement)
* Sealed beams
* Light bulbs
* Components not installed by the vehicle manufacturer
* Sheet metal
* Body panels and parts
* Convertible or vinyl tops
* Molding or bright metal
* Drive belts and specified hoses
* Air and water leaks
* Wind noise
* Contaminated fuel system
* Exhaust system
* Catalytic converter
* Brake drums/rotors
* Brake pads/shoes
* Shock absorbers
* Spark/Glow plugs and wires
* Manual clutch disc
The point is KNOW YOUR WARRANTY!
P.*. SMART MOVE getting a GMPP rather than an aftermarket service contract. They vary widely, where the GMPP is easy for the service writer to deal with, and avoids headaches for you and them.