Well unfortunately this has turned into a which car is faster thread - kind of a bummer cause I think we can all agree, nobody agrees on what "faster" really means
That said, C&D Is one of the magazines that adjusts for temperature and climate. R&T (I think) was famous for not doing that and would actually report the ambient temp when they did the testing. So at the end of the day, I think C&D is the most reliable - still, as you can see by their article posted, there are often differences in the same car (one M3 runs faster than the other). But that happens in real life too. I suspect it is with how it is broken in - but OMG, let's not get on that topic!