Thanks for the comments. I think I'm inclined to do earlier, and more frequent changes than Porsche recommend, especially with the engine being turbocharged. Toplesswhitelegal, what you say sounds good advice.

With regard to the Hummer H3 vs H2: the H2 was not an option because of its size and impracticality. Where I live [I'm in Europe] it is not possible to register a car in my jurisdiction which is more than 2 metres wide. Of course the diablo is 2.04 metres wide, and I have to keep the Lambo registered in another jurisdiction, where I can also claim to be 'resident'. Its a hassle, and it ruled out an H2 for me.

I like the H3, the build quality is good, and there has not been a single issue with it in over a year, but the car is more about style than substance. I would sell it tomorrow if my wife would let me.....