It's one of the most important performance car launches of 2012. And we've given the all-new, 991-generation Porsche 911 its toughest test of all. It meets 10 key rivals on Welsh roads in the latest issue of evo Magazine, on sale now. Here, Richard Meaden puts the standard 3.4-litre 911 Carrera through its paces. The best Porsche 911 yet?