Dale- Where do you think the Japs test their cars? Australia. Alot of manufacturers test there cars in our backyard, due to space, and the lack of speed limits... Which is why capping the speed limit at 130 for NT was stupid, as it takes money out of the local economey.
Depending what is done to a car, i dont see why a professional clean(getting done shortly) and a new thermostat(45$ genuine) wont have it running sweet. Keep in mind newer cars run hotter to make them cleaner/more efficient.
Also when it comes to thermo's, dont touch davies craigs, I went though a book at Nissco, and there were fans that would flow heaps more than 2x 12"DC's, for less money, and they were thinner... i can check the brand if needed. That said, i have two brand new Davis Craigs in the shed.