The E30 M3 was car developed for Group A homologation. Unfortunately Group A touring car racing doesn't exist anymore which is a big pity. None of the major touring car specs today are in any way related to production cars (eg DTM, Super 2000). In short there is no reason for BMW to develop a professional motorsport vehicle like they did in the 1980s.
To me a proper "M" car is one that is suitable for use on a circuit. It means the engine, brakes and transmission all have sufficient cooling to do at least around 15 or 20km at maximum attack around a circuit without anything severely overheating or stop working. Obviously you want some decent performance and handling as well.
I think a M car should be less luxurious than a top range BMW. I would prefer if BMW made a better distinction between the features available in M cars and those in the luxury range. The marketing of the "M" cars seems a bit confused because they seem to be perceived as the "Most premium" product in the BMW range. There is some differentiation of performance cars like 1M, and M3 as they cannot be ordered with sunroof, but that's about where it stops.
What I strongly disagree with is the BMW SUVs like X5 "M" and X6 "M" (?!). It seems like a total abuse of the "M" performance brand. Porsche also sell SUVs for people who want a fast family transport. However those SUVs are not really intended as "Motorsport" products. I have never seen a Porsche Cayenne GTS, or GT3. Who knows, maybe Porsche will offer that to compete with the BMW X6M.
