What Are The Most Unreliable Cars?

What are the most unreliable cars/makes? Jaguar used to be amongst them with their lucas electronics until Ford bought them. Now they are in the top 5 on JD Powers list as far as reliablity. Would you say that Volkswagon & Audi are amonst the most unreliable? Their extended warranties are a fortune... I just bought a new Audi TT
Eric.....