One of my biggest hangups with the new M models is BMW's bizarre decision to favor increased muffler size (and four cool looking exhaust tips) over fitting even a space saver spare tire. I post on this every now and then, but the linked thread got my attention and so I thought I'd do so again.
Can you imagine being on your way to a client site, having a flat, and having to wait by your car while it's flatbedded to a dealership? Or being on a freeway late at night, just wanting to get home, and having to call Roadside Assistance because you hit a nail? I've used the spare tire on several of my cars in just these situations; it simply blows my mind that BMW doesn't see the need to give a real spare tire.
IMHO, if they absolutely have to have the fancy chrome exhaust system, they should at least provide the option of run-flat tires. I realize that they decrease performance somewhat, but the notion of standing next to a brand new 50K+ car on the side of the road waiting for a tow truck because the tire is flat is just ridiculous.