Coming from a Corrado there are couple things youll find in common with the E36, mainly the nice plain simple mechanics, robust design and awesome six cylinder engine.
The biggest obvious differences are the configuration (FF vs FR) and the associated driving style. Although both cars have minimal driver AIDS, the Corrado will be far more forgiving to its driver and the BMW will be far faster in basically every situation.
The next big difference are the costs. The basic component costs for an E36 M3 vs the cost for parts on a 90s VW are worlds apart. VW front top mounts c.£30, E36 M3 front top mounts £100. Thermostat, £8 vs £50. Water pump £30 vs £80. Six bushes on the VW to replace (two of which dont wear), 13 bushes on the E36 M3, at the rear alone. £600 for new front wishbones on the M3.
If you go on to Pistonheads now and browse a few M3 adverts very few, if any, will list any important maintence that has been carried out to the cars. Whats the point in owning a performance car that doesnt go, stop and turn how its meant to? A worn out M3 may as well be a 318 for how bad its going to drive and given how little important maintenance is listed in these adverts I wouldnt be suprised if those cars are as bad to drive as mine was because theyre getting on for 20 years old and any original suspension part will be completely dead.
Like the VR6, the S50 is a mechanically very strong engine, forged top to bottom. There is one mechanical weak link in the engine, the big end bearing bolts. It was a high revving engine for its time, the big end bearing bolts can stretch if exposed to long durations at high revs. Bearing gap increases, oil pressure drops, shells can spin, engines can die. Easiest fix is a set of ARP bolts for the bottom end pretty much future proofs the engine. Mine has those.
The Vanos issues arnt the end of the world. On a 3.0 you can change the important seals in a couple hours. There are electronically controlled actuators which can fail (mine were fine) but the EVO has twice as many and theyre expensive to replace if they die although i expect most failures would be due to failed solder joints.
With regard to the 3.0 vs 3.2, the main difference in the engine's character is a bigger lump of torque in the mid range. The 3.2 has an extra 20lbft over the 3.0 in the low to mid range which makes is more civlised with more easily accessible torque, but then some people like the way the 3.0 wants to be wrung out (but that could be 3.2 fanbois vs 3.0 fanbois, just pick what you like)
Heading backwards we get to the gearbox. 5sp vs 6sp. 5sp is by all accounts utterly bombproof, something youll be familar with in the Corrado. The 6sp can have problems but youll have to google those.
The reason i bought a completely bottom of the barrel car was that i expected everything to need doing. Unless you find a museum piece for sale, I doubt you can buy an E36 M3 at the moment where every single suspension component has been renewed or uprated. Thats what i was aiming for with my car, though, its how my cars just are, so having a car with 20 years of wear in the suspension wasnt really an option so there was not much point in buying a "dearer" one for me as the adverts just dont list any important work having been carried out.
Colours, im biased, but Helrot red is amazing. It stands out in a good way and given there are almost none on the roads now, it reminds me of the woman in the red dress in the Matrix in the way it stands out. If I could chose, Id go for one of the purple/violet colours, they were a big thing in the 90s in the same way as VW had their Mulberry and mystic blue colours.
Now that my car is (mechanically) sorted its a hoot to drive. youve got 230lbft of shove from low revs which is enough. Its not a hot rod but they werent never meant to be but its plenty quick enough for the road and with no driver AIDS its capable of asking you some very big questions if you get cocky, the sort of questions a VW wouldnt imagine asking you, which i think is nice, you have a certain respect for it.
Compared to an E46? E46s are going through a painfully chavvy stage in life, the E36 is past that. The E46 is newer but ive not driven one for so many years I couldnt compare them.
Id say an EVO rear diff is an essential mod on a 3.0 unless you plan to do a lot of long distance driving (and if you are, it might not be the best car for you anyway). Also, being 20 years old, the car is unlikely to ever be totally perfect. Next on my list are door and window rubber seals and interior clips, but if you like fiddling with cars that sort of thing wont be a problem