Don't really know, but how else do you explain the duds, where everything seems to go wrong?
Probably the scariest thing about forking out the mulah for a new car, as we have no lemon laws. Yet.
There are also big (well noticable) differences in engine performance from the same model. Drive alot of pool cars for work. Some are freaks of nature and go like the clappers. Think it has much to do with the way they are "run in". We had a VS Ute that was thrashed from about 7kms on the clock. That thing went harder than a schoolboy at a stripshow.