I have the CTEK 3300,
http://www.amazon.com/Multi-12-Volt-...&keywords=ctek
It works on all the vehicles in the household and obviously it did its job for my old 335i and my m3.
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Current - 2012 AW/FR E92 M3 | 2014 AW X5 | 2015 MB S550 | 2016 RR V8 (White FTW)
Mods - BPMTune Stg1/Servo, Euro Visors & Side Mirror, IND Gloss Blk Pkg, OEM Perf. CF Trim/Spoiler, Grills, Lights, Pedals, Umnitza V4 AE, ModeCarbon GTS V1, 19" HRE P40
Sold - 2008 BSM/Black E92 335i