Totally amazing cars. Absolutely love everything about mine. They do everything pretty well or better. Speed, handling, comfort, quality, reliability, build quality, everything about them is better than 90% of cars out there. The power is excellent and so usable you don't have top bother with the gearbox if your feeling lazy, with over 200ftlb of torque from idle rising to around 370ftlb from 2000pm to the limiter, she will pull from 10mph to 186mph in 5th gear. :lol1:
As for daily driving, again, it excels, the big V8 heats up fast and you can potter to the shops with no drama and she will sit outside looking subdued to all but those who know what she is.
They don't feel anything like as big as they are once you get the hang of them, and you can easily push the limits more each week. It may be a few weeks before you disable the incredibly competent DSC though, shes a heavy girl at the back so needs your wits about you to push hard in the rain with DSC off. With it on, your grandma couldn't lose it, honestly, the computer would almost forbid it. lol
The quality you are buying and driving is what swings it for me. They drive better at 200,000 miles than any Ford, Subaru or Mitsubishi Lancer does when NEW. And so they should, don't forget, fully loaded, these cars were £65000 only 6-7 years ago!
Toy lovers will be at home as the list of toys is massive on an M5. lets see, here is my spec.
(In the order i can think of them...):5L V8 400BHP
6 Speed Manual Gearbox
18" Alloys
SAT NAV
TV
Teletext
Dual Zone Digital Climate Control
Grey and black Nappa Leather Interior
Brushed Aliminium Trim
Electric Heated Seats with Drivers Memory
Centre front and Rear Arm Rest
Premium Sound System with 6 disc changer
On-board Computer showing MPG/temps etc
Built in laptimer and stopwatch (handy at the ring)
Cruise Control
Sports Mode (Improves steering and accelerator ratio)
Traction Control
Multi Function Steering Wheel (controls radio and cruise control)
Electric rear privacy blinds
Electric Tilt and Slide Sunroof
Electric windows all round
Electric Folding Mirrors with memory
Interior and exterior mirrors are all automatic anti glare. (They go dark when bright lights shine in them)
Washer jets, and mirrors are all heated.
Multiple Airbags in dash, wheel, front pillars and all four doors
Power Assisted steering
Xenon Head Lights
Angel eyes (You must upgrade these to 7000K LED's)
Front Fog Lights
Auto Tyre pressure monitoring
Parking Sensors front and rear
Mirrors drop to view kerbs automatically when you select reverse. (Switchable)
Remote Central Locking
Alarm/Immobiliser
Automatic rain sensing Wipers
auto headlight activation
Anti Lock Brakes
Toolkit in boot
DECENT First aid kit built into car
Rechargeable torch built into car
Warning Triangle built into car
2 Main ignition keys with remote controls built in
Full tints all round
3 driver settings that set the position of: Seats, steering wheel, mirrors and aircon. Great for other drivers.
Auto key charging. The remotes charge up in the ignition automatically. No batteries in them.
Disarm key personalisation.
(When Nicole gets in with her key, the car sets all seats, mirrors, aircon, steering wheel etc to her settings. When i use my keyfob to disarm, it sets it back to mine. No more changing seats and stuff... bliss!)
Do any other features actually exist? 
Some light viewing for you...
YouTube - Top Gear
YouTube - E39 M5 "Star" Madonna Guy Ritchie BMW Films
Ive owned a lot of good cars, and ive driven more fast and high quality cars than most, and the E39 M5 is the best daily driver i have ever owned. These are pre stupid road tax increase too.
Problems?
They don't have anything you would call common problems, they are massively over engineered.
Bushes take a hammering. Buy powerflex, fit and forget.
Ensure vanos rattle on startup goes silent after no more than 2.5 seconds.
Have someone scan the ECU for fault codes, it has a very serious management system and nothing gets passed it.
camshaft sensors are quite common, they last years but go unnoticed as the engine runs well without them.
MAF's fail or get contaminated. easy to test from the display on the dash if you know how.
Good test of the vanos system sensors.
Drive in 2nd. 2500rpm. Nail it. Should pull quite progressively to 4k, then pull harder round to the limiter.
Drive in 2nd. 4000rpm. Nail it. Should shove you back in your seat like a turbocharged car and pull progressively to the limiter.
Servicing costs:
Well, the late ones,
(Which you SHOULD buy) don't use oil, so change every 6000 ish ideally. Everything else is standard 5 series really, so cheap to run if you can afford the fuel costs. Nothing really to wear out as per any modern 5 series.
A few pics of mine...
Inside the sump pan after 105000 miles.
