Saturday morning, I was fortunate enough to get a long test-drive in a 2001 E39 M5 without the salesman. The car was used, with about 19,000 miles on the clock (to me, that was good - it was broken-in).
First of all, I have a lot of seat time in the E39 540i (6-speed), and I just sold my E46 330i (5-speed), so I am used to quick BMW's. The M5 makes both of those seem docile.
The car was morning-cold when the manager threw me the keys, so it took a good 5 minutes before I could redline and hear the engine sing. Once it did, I was in heaven. Unfortunately, the city was unfamiliar to me, and at first, I was unable to find any real place to open her up. Stoplights were frustratingly all green (wouldn't you know it), and traffic was heavy...so I searched for an open road. Minutes later, I found a side street next to a business park (it was Saturday) that was long, flat and desolate.
I pulled over, shut off DSC, turned on SPORT, and let her rip. The tires spun for what seemed like minutes... then I shifted to second. THE TIRES SPUN AGAIN for about three more seconds and the car twitched left and right. Redline in second and I swear I got another chirp into third... the tach climbed, then I ran out of room. Wow!
On the road, with the car in second gear at 4000 rpm, nothing can touch you. It really is a beast. The engine sounds beautiful (like the 540i - which already has a wonderful exhaust note - on steriods)
Turn the SPORT button on while cruising, and the car lurches forward. I am not kidding, it is like switching on more horses. It is frightening.
Anyway, it was the most powerful car I have ever driven, and I was very impressed. The transmission is different from the 6-speed in the 540i, it has wonderfully shorter throws. The suspension is tight, yet not jarring.
In case you are wondering, it does feel like a big car, so the M3 still would be my choice on the track. However, give me an M5 to slaughter people on the freeway, or from stoplight to stoplight.