[s-cars] Extended Warranties/Cert. Pre-Owned

[Calvin & Diana Craig]

My wife and I are shopping for a 2000-2002 used Audi, most likely an A6, but
I am not sure, don't worry the S4 isn't going anywhere :)  Anyway, I was
wondering if you had to buy an Audi certified pre-owned vehicle to be able
to extend the warranty or if you got that chance at the end of the 50k mile
warranty period as a matter of course no matter what.  Or, can you buy an
extended warranty worth a hill of beans from the dealer when you purchase
the car if the car is not "certified pre-owned", whatever the hell that
means anyway.  Thanks!
--Calvin