The M5 is a beast. But it comes down to this.
The extra cost gets you a limited production high performance 500HP+ engine and tranny (about $15k) and forged wheels (another $5k).
I would never be able to open up that kind of power. As it is, I can't open up a 535 all that much.
To me, the key to the M5 looking awesome is the color and wheel choices. Some of the color and wheels choices are just nasty.
2013 VW Golf TDI