Audi Cabriolet - Heater Matrix

I own a final edition Audi Cabriolet 2.6 which I have enjoyed for the last 11 years. It has been maintained to a high standard, it has cost a lot of money over the years, but I have enjoyed it so much I don't mind, and when I listen to that V6 it sings. My mechanic has had to dismantle many an engine of half it's age and mileage. I don't agree with a number of the "negative" points I read in reviews namely seating in the back and handling, these are perfectly adequate for me, and yes the back screen becomes hard to see through, it is only plastic though after all. The later glass ones fall out after 10 years, I'm told. My most major concern came up this year when I found my windows steaming up, loosing coolant, wet carpets in front wells. IT'S THE HEATER MATRIX!. Major job yes, dashboard out etc. Fortunately my mechanic said "Don't worry, we'll sort it". Can't afford new cars at todays prices, and I was warned of the high oil consumpton on some engines (a litre per 6 hundred miles ish), nearly as bad as my old rotten Ford 105E!. I'm told you won't be able to tell if an engine has had new rings when buying 2nd hand, and it will probably be out of warranty. So hopefully I will be enjoying my Cabriolet for a good while yet.