Ha ha you keep living the dream. It's the same car underneath with a few tweaks to upgrade the interior and reduce production costs and give it the new VW corporate nose. This was well publicised in the press and is the official line from VW.
living the dream? well i've have a mk 6 and i had a mk 5 gti so i can actually make my own mind up rather than reading what a fat sweaty journo tells me in some magazine. oh and the engine is different so its not really the same car is it? plus it doesn't drive the same. and the interior is different.
the same? hmmmm.
Jeees you guys are soo picky, some different shaped seats, a few new knobs, some extra soundproofing and some extra bits on the engine do not make an all new car! VW have stated in their press releases and on their website pre launch that it was not "an all new car" but an upgraded and tweaked MK5 to make it better and more efficient to build and run.
Ok let me try and put it in terms you may understand. If you tried to fit the running gear and interior on a MK4 into a MK3 or a MK5 it won't fit, the body shells and platfroms are different. They are different cars. If you want to swap the running gear and interior from a MK6 into a MK5 you can because the body shell is the same, they are essentially the same car.
nick