Collin B 
2004 BMW 5 Series Sedan 525i 4dr Sedan (2.5L 6cyl 6M)
It's a trap!
 I owned a 2004 530i that I purchased in 2013 for a year and six months and 20,000 miles.  In those 20,000 miles the vehicle needed more than $5,000 in maintenance and repair items, and this was a clean 1 owner example that had been meticulously maintained.  It needed 4 new brake pads and rotors for $2200, 4 new tires for $1200, all new PCV hoses for $850, Spark Plugs for $300, transmission fluid and filter exchange for $900, water pump and coolant for $75 (DIY), $200 for a sunroof leak and the subwoofer it took out (DIY), and $300 in oil and filter changes. I cringe when I think about how much I spent on this car, only to have it totaled in a flood.  However, it was the most solid driving, comfortable and beautiful car I have ever owned.  All of the features it had worked from the heated steering wheel, to the complex iDrive system, even after 11 years and 120,000 miles.  The engine still purred like a kitten, could bounce off the rev limiter, and the car would still hit 155mph and pull 0.90g in the bends just like when it was new.  It never broke down, nor had any problems. All of the items listed above are either wear items, or were replaced preventatively.  I can't imagine owning another BMW of this age, as the rubbers and plastics used simply don't hold up over time, however I'd definitely consider owning another newer one.  This car is not for the faint of heart, and if you just need a cheap luxury car to drive everyday, I'd go for a Lexus.  On the other hand, if you like to work on cars yourself, or want a fun daily driver and are willing to pay for it, the BMW is the best you'll find.