M6 is not best car for standing drag races...
It is very difficult to find a traction even for stock car.
I agree with
Twitch Massacre that using LC is waste of time, i also do my best 0-100km/h and 1/4 mile without using LC but just "playing" with acceleration and gear changes. (best 1/4: 11.466@128.4mph) which is I think NOT BAD for stock RWD car
However roll race rollraces is a different story
Stock car can keep up with 991 Turbo S, 458 Italia, it will kill every RS and AMG.