Welcome
Congratulations for Your M6 - great car.
It's definitely not 0-60mph car but in some conditions it might be very fast.
First of all: i don't use launch control - it is rubbish and can do only good burnout... i always turn my traction control totally off and then just put the acceleration into the middle and "play with grip" after that - immediately put 2nd gear and full throttle
It's hard to have repeatable 0-60 times in RWD cars this method, but my best was around 3.6seconds.
Here You have one of my vbox results (not best) which I've found:
Stock car, with competition package (575hp version)