MB bolts generally have their threads rolled
For the typical sizes found on cars and the like virtually all commercially made bolts have rolled threads. Once you get into really large diameters and/or oddball sizes threads may be cut but pretty much everything else has rolled threads because it's cheaper (faster than cutting threads and chipless so no waste) as well as better. About the only time i come across cut threads on commercially made fasteners (and the difference is typically obvious to the naked eye) is with studs and even then you have a choice unless you want grade 8.8 or higher in which case it's typically rolled threads only
For the vast majority of things i fabricate i use flutess thread
rolling taps over conventional straight or helical flute cutting taps. Half the time the extra strength of the rolled thread is immaterial, i use 'em for speed and lack of chips/swarf in any compatible material for sizes under M10
MB don't make bolts and in most cases probably won't design anything either, why bother when you can select a spec that'll do the job and is available off the shelf
Sometimes the fasteners that OEMs use are harder to find elsewhere but often the difference is something that only mattered when the car was made, things like this
long thread lead-in which is about making the fastener almost impossible to cross thread for example
Occasionally you come across a weird grip length i.e. the bolt has an odd length shank in relation to it's total length. That can make a difference on suspension bits as the nearest 'off the shelf' thing that'll physically work results in a portion of the threaded section being subjected to bending loads when the fastener is used in double shear instead of tension. Last saw that one on an old aircooled VW, a grade 12.9 cap screw that does double duty functioning as a pinch bolt and a cotter pin on a ball joint. With generic 12.9 cap screws the grip length is wrong and some of the threaded portion ends up being used as the cotter pin
If the grade, overall and grip length can be matched then pretty much the only risk of buying a generic bolt is counterfeit cheapnese tat (as already said) and if buying from somewhere reputable i'd say the risks of that are probably no higher than going to MB and paying several times the going rate
The electrolytic corrosion thing is rarely an issue as most manufactures use plain ol' BZP, yellow passivated or black oxide fasteners which are a lot easier to find than uncoated. Not relevant to a suspension bolt but as magnesium castings become more popular for weight saving reasons the corrosion thing does come into play with not only aluminium bolts being used but weird flavours too instead of the more common 7075-T6...
http://www.kamax.com/fileadmin/user_upload/dokumente/veroeffentlichungen/alu_fast_for_magn_comp.pdf
