As a 22 month owner of an LCI F10 M5, nearing on 35k miles in that time, this has become very much a daily driver for me.
I searched for a long time for my ideal M5 and had to make two compromises on what was near on the fullest spec'd M5 available at the time.
It had 19k miles on when I bought it in April 2016 and there is not a single day that goes by when it doesn't cease to amaze me at how capable it is. It's brutal in a straight line, blistering in fact, and it never ever gets old. It gets addictive.
Some of this might help:
What age?
63plate onwards ideally (defo LCI at this age)
Nice to haves?
Comp pack nice, but not essential.
Most of the M5s I've seen had a 5 year, 50k mile service pack. Look for that. Other than fuel and tyres (more on those in a mo) and depending on the pack chosen, you won't spend a thing.
I've had, two full services, all oil top ups (in relation to the engine run in) and a full set of pads at the grand expense of £0
M Sport Multi Function Seats (an absolute must)
True LED Headlamps (look for the BMW LED marking on the headlamps).
Power Performance and Economy?
560bhp is manufacturers claimed output. I've never seen an M5 pull a figure that low on the rollers, most sit around 570-580 out of the box
My complete average mpg in my ownership is 20.1mpg. I do see 30mpg on a sensible motorway run. Normally I'm, around 18-22mpg
What to watch?
I've got one of the "new owner" engines, which basically means, the first owner, (i'm the second), couldn't quite wait for the run in period. Therefore I use oil, a lot, 1 litre every 5-7k which is well within BMW acceptable guidelines
Tyres:
The first few years of F10 M5 came with MPSS as OEM. Due to a shortage of this tyre sometime in 2013-14, these were swapped for Pirrelli P Zero which are an absolute shocking tyre (for this application at least). They are skittish, bounce, loud, and honestly feel like run flats (they aren't).
As a minimum, get some MPSS back on there, or MP4S. I've just had a complete set of the latter put on at 52k for £880 fitted. Prior to that, the fronts went from 17k miles to 52k miles and the rears have gone 17k > 32k > 52k
In answer to other stuff:
Easy to cook the brakes in an M5 on track... expect to go through a set of pads per track day & fluid change if you're not careful.
Don't worry, this isn't a thing unless you're a goon. Competition Pack helps with this, but again, the normal setup is fine and will quite happily see you around a track for most of the day. Yes, it's a heavy car, but the Engine and DCT combo is exceptional when it comes to engine braking. If you're not able to use that to you advantage and brake to scrub the last bit of speed off, why are you even on a track in the first place.
They are just as much a weapon with the right tyres in the corners as they are on the straight, and when you do line it up on the straight, most things will quickly come and go in your mirrors.
Yes, they can tow. They make cars designed for towing look stupid. Obviously not ideal, but still an option.
Happy to answer any other questions you might have.