Stock M135i equipped with the 8 speed auto is quoted an identical 0-100 km/h with the 1M, while the xdrive is expected to be faster than both the rwd and 1M, at least up to 100 km/h.
As an active follower of 1M forum, the fastest we have heard from a forum member was 4.4 sec to 100 km/h on a bone stock car, 0.5 seconds faster than BMW advertised figure. Moded cars can go faster, there are even sub 4 second cars, both 1M and 135i if they are fully moded.
So, I am neither surprised nor much impressed with the Hartge tuned M135i time; it doesn't seem to me much progress over stock car, in fact Chris Harris clocked a stock M135i at 4.4 to 60 mph as you all should remember.
Check this thread which includes some good info and discussion on these times:
http://www.1addicts.com/forums/showthread.php?t=668716
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"The mark of a great car is one whose overall competence exceeds what you should expect from its individual components and the 1M does just that", Chris Harris.
BMW 1M-SOLD-: TECH: Evolve Race+N55mids, Evolve IC, Michelin PSS, ER cp, aFe filter, CDVx, Vorshlag camber plates, BMS OCC EXTERIOR: trunk spoiler, blacklines, black grills, IND goodies INTERIOR: Alcantara steering wheel, steel pedals, custom mats, MPower e-brake.