The E39 is one of the most timeless designs ever to befall a saloon car, and the M5 is the kingpin. This was the baddest sedan that could be bought back in it’s day and now you can pick them up for the price of a new Corolla. That’s right, the BMW M5 can be had in all of its glory for a solid price that ranges from around $14 grand for the most abused to over $40 grand for the most immaculate. Overall I would consider $17-27k a solid price range to look in for these cars, because any less is a real risk for problems and any more you can likely find better options. In this middle range cars tend to have some decent mileage on them but not enough to deter a purchase, I call it being healthily used, generally 40-80k miles.
The E39 M5 is the definitive sports sedan; with its driver-focused feel, 6 speed manual transmission, and 394bhp V8 it is sure to entertain even the most discerning driver. Stock 0-60 mph comes in bit under 5 seconds and if you take the restrictor off it will top 175mph, not bad figures at all even a decade later. Modification wise I would advise you to keep things to a simple exhaust and chip and stop unless you are someone who has tens of thousands to spend on a supercharger or turbo kit for the car as most parts will yield little gains on the motor alone. The V8 is already quite performance tuned from M division as is, so it needs forced induction to see much more power.
If you are looking at an M5, then you likely already understand that it will require more money from you to maintain on a regular basis. It also isn’t very good on gas and only takes premium fuel. If you are not aware of all this and care about saving money in such aspects, then an M5 is not the car for you.
The E39 M5 is a well-loved Bimmer and is seen by many as the definitive M5. Because of this widespread love for the car, this M5 is expected to appreciate over the next few years much like the E30 M3 has recently. When looked at in such a light, the M5 is really a good buy for someone who can really take care of it because it may well yield a profit.
Overall the E39 M5 is seen as one of the greats in the modern car spectrum, it offers a very focused and exciting driving experience while still being practical and comfortable. It is a fantastic car in all regards that matter to enthusiasts, so if you are one and you get a chance to purchase one of these, believe me you should.