Are you sure it was the 2013 S6?
With what is going on out there with new S6, (2013) E63AMG and S8, they should all leave M3 with a view of their tails at least from get go.
I would like to know how the new M4 will compare to E63's predicted 0-60 3.4 sec acceleration.
Also, if it was the 2013 S6, he could of been possibly on his break in period where he just let you go.....
Current: 2016 F10 535i xDrive AW w/ Black Dakota, ZMM, ZCW, ZDA, ZDB, ZPP, 688 & Black Grills.
Retired: 2011 E92 M3 -AW
....ED April 29th, 2010
Retired: 2007 E92 335i -Space Gray.....ED Oct 19th, 2006