Sarah, I take it your car is out of warranty. Its not really playing with a straight bat, trying to get a company to remedy things that are already playing up surely. This must come close to fraud.
Well, I don't know if I would necessarily agree with that - faults can appear at any time, and I'm sure if the company was inundated with a claim on the day the warranty commenced, then they may be suspicious (but what can they do?). They don't insist on a full inspection of the car prior to the application's approval, and since (most) of us aren't mechanics, how can we be held liable for knowing a fault existed?
I wouldn't say it was fraudulent - bordering on the unethical, perhaps. But I would do it!
Noel, the warranty is transferrable to the next owner (a real asset for a private sale).
Sarah, from what I gather, no warranty will pay for diagnostic checks (otherwise, this could be open to abuse from paranoid owners, and over-zealous garages), but if a fault exists that is covered, then they are good at pre-approving repairs. I have no connection with the company, other than being a satisfied customer who will put my car on their books once its own warranty expires.
Hope it helps.