Coldlist - I hate to correct you old chap, but I think your assertion that M5s did stand out traditionally is way off target. The M3s did with their power bulges, but M5s have always looked relatively ordinary.
Here are some pictures I took at the F10 M5 launch event which I attended in Spain.
E28 M5 - The first gen pretty much had a standard 5 series body. Hood is ordinary, bumper is ordinary, fenders are ordinary. Again more like a standard 5 than the F10 version.
M5 E28 has a unique spoiler lip as so no the bumper is not ordinary. You could have an M Technic Spoiler package but those are rare, most were sold in the UK. The M Technic Spoilers were the same on M535i. The 16" cross spoke wheels are unique for M5, the standard metric wheels were shared with E23 and E24 models but unique within the E28 range.
E34 M5 - The second gen M5 had some fancy door mirrors, small rear spoiler, front lip, white turn signals and the signature M-Double spokes, but other than that was also pretty plain. Less differentiation from standard 5 than the current model has.
M-Technic mirrors were an option on all 1993-1995 M5 except the US 1993 which had them as standard. But they were standard on some more E34: 1994 525i Sport Limousine, 1995 M540i, 1995 540i M-Sport and 1992 M5 20 Jahre. The front bumper is unique for M5 (one for cars built before 2/90 and one after) the rear bumper is the same as E34 with M Technic Spoiler Packages, the same goes for the side skirts.
The wheels was made in three different versions: M System I (M5 3,6 (except US 1993's) M System II (M5 3,8 1992-1994 + US 1993 3,6) an finally 18" M Parallel on 1995 M5 + 1995 M540i. White indicators were on mounted on TWO M5 from factory, this 1995 Daytona Violet + an 1995 Schwarz Mica EVERY other M5 E34 had orange indicators from factory. There are none M5's with white indicators from factory among them a friend of mine former 1996 540iA Touring.
Standard on M5 E34 were that the lower part of the car had contrast color (through Individual you could order this on an none M5 + you could order your M5 without contrast color.
E39 M5 - The third gen M5 added a nice M aero bumper - more than just the lip on previous models. However hood and fenders look pretty standard. Mirrors are more ordinary than the ones on the E34 M5. No side vents. Generally a pretty regular looking 5. The m Double spokes are very similar to those on the E39 540i. (no they are not, but E39 had the 18" M Parallels as an option) Also in this gen, BMW started providing clear turn signals to M-Sport models which killed the exclusivity of the m turn signals on the E34. (no, totally untrue)
The kidneys were unique on the 1999 and 2000 M5's then they came on facelift 535i and 540i. The front bumper is unique for M5, standard E39's with M Sport Packages has a bar in the hole below of the plate holder. The mirrors are unlike E34 only factory mounted on M5 + the quad exhaust and the wheels is also unique for M5. So E39 has more unique features then E34. Except for the front bumper you could buy an E34 with EVERY M5 feature including M5 door sills.
E60 M5 - The first one which looks meaningfully different than a non-M 5. However it is in contrast to the ordinary look of the previous M5s. And the things which differentiate the E60 m5, are also present on the F10 M5 - fender vents, wider fenders, mirrors, wheels.