The GT3 is absolutely twice the car of the M4. It's not just about 0-60 (which is is 3.0 seconds in the naturally aspirated 911). 4 wheel steering? Best sounding sport exhaust? Yes. I am on the fence about getting one but at $140k it's the best deal out there and an alternative to a 458 not M4. Is the m4 better than the cayman? Not a better driving car but better presence. Going from an E46 to an E92 to a 911C4S I can tell you those cars are not in the same league in terms of steering or performance? The M3/M4 are great cars but if you want a "sports car" vs a GT car the 911 is hands down more engaging. The M6? Have you driven it? Seriously least special car out there. The Ferrari 458????? Without question the single greatest car I have ever driven in-terms of everything. That being said if the M4 is that special when I drive it and I splash water on my face and realize spending GT3 money on a car is silly, it's still on my list. This video starts out a little slow but I'm assuming you aren't aware of the tech in the GT3 so check it out
http://www.autoguide.com/auto-news/2...fications.html