I don't want to offend anybody, but I am having trouble figuring out why so many folks get fired up about what they consider excessive oil consumption. When I purchased my Porsche 911 (in 1966), I was appalled at the expected oil consumption as listed in the Owner's Manual (One qt. every 300 to 400 mi. is normal - and that's what I got - and still get at 53,000 miles.).
It is clear to me that the oil consumption on my M5 varies with how hard it is driven. Sometimes a qt. every 3,000 mi. and sometimes a qt. every 500 mi.
I don't feel comfortable accepting high oil consumption, BUT ... I bought a performance car, just like the Porsche was in 1966 (I still have it and love it, as I do my M5). I paid $ 80,000 for my M5 (ordered new), and I just replaced my tires at 31,000 miles (threads showing on right rear). AND, THEY ARE EXPENSIVE, TOO! (more than all the oil I will purchase in my lifetime).
I should note that I have three other BMWs (none Ms). All driven "briskly" and all three use almost no oil or maybe a qt. every 4,000 to 5,000 miles. And, I just got rid of my first BMW, a 1980 320i which had 320,000 miles on it and never used an ounce of oil ... and the engine had never been apart.
I own two high performance cars ... each uses what I would consider a lot of oil, but when I "lay the hammer down" I get results ... NOW and beyond - the Porsche has been driven at 132 MPH for over an hour and the M5 many times at 140 MPH, and once at 150 and 153. Man I love 'em ... and when "push comes to shove," oil is cheap ... and, at least in the aircooled Porsche, is doing some good in cooling the engine as it escapes the confines of that marvelous engine. I hope my M5 lasts as long with the same pleasure I receive from the Porsche.