I have had my 540 for almost 5 years now. I love the car, fun to drive, fast, reliable. Gas mileage is poor but it is a big V8 under the hood. Have only done routine mileage related repairs that any car would need, only at a much higher cost and we do all our own repairs. Hate to say it has been hit twice and is the only 10+ year old car I know of that was totally covered for a combined 10k of body repairs. My only re-occurring complaint is the need of new tires, alignments more often then most cars, I only put 20k on it in 5 years and I am on my 3rd set of tires. Oh and for winter driving, this car stinks, which is why my next auto, later this year, is the X5!! I do love my 540 though!
Engine, exterior design, smooth ride, excellent handling at high speeds.(had up to 110 mph and didn't even know it!)
Cup holders are the worst, I have the standard audio system which is terrible and back seat leg room is minimal. Repairs are costly even when your a mechanic.