This one is controversial, there are a lot of stunning 6 series out there with happy owners, and I am not dissing your cars at all, the fact I went out with my money and bought one should tell you what I think of them. This is my honest opinion of owning the one I owned.
I got on in 2010 an 04 645ci for €15k I sold it 6 months later for less than €10k after putting 5000km on it. The e63 was introduced in 2003 the first Irish car being 2004. The 645ci is a 4.4ltr V8 2producing 45 kW (333 hp) and450 N·m (332 lb·ft) @ 3600.
I bough this car cause my old car was stolen and I needed a car. I had seen a similar car owned by a chap called Davy at a BMW meet, and I though it was lovely. The Bangle styling is IMHO terrific, although it is dating a bit. BMW has gone more angular these days and the e63 curves are gone, but I do think this is a design classic.
The engine is a lazy V8 with good acceleration, reasonable fuel consumption given the capacity around 22-25 mpg surprisingly combined. But be under no illusion this car is designed for the American market and is a grand tourer not a performance car. The engine gathers speed well but without and drama, the ride is pretty comfortable but not that comfortable. The engine sound is loudish but not that loud. The steering is heavy but imprecise and the turn-in is wallowey with a good bit of roll.
The auto box is not as good as the later ZF transmission and tends to shift too early even in sport mode and had an annoying habit of shifting mid corner.
The interior of this car was very nice, although cup holders are an afterthought and were missing from my car. The newer Idrive system is easy for anyone who can tie their own shoes to use.
I had no real reliability issues although my ownership time was limited. I replaced a suspension part, updated the software. Things to look out for are steering wrack issues especially on dynamic drive versions, and coolant problems with the engine. The V8 was well tested at this stage and quite reliable. Any electronic faults are costly as these were flagship cars at the time €110k euro plus machines.
I sold mine cause of the handeling. It didnt suit me. It not that I am a fantastic driver of anything but I didnt have confidence on the road, the steering is vague and the engine for all its capacity is not that sporty. I suppose I bought a grand tourer expecting it to be something else.
Pros.
1. Lovely looking
2. Nice interior.
3. Still a head turner.
4. Cheap to buy.
5. Reliable...in my experience.
Cons.
1. Boat like handling for a BMW.
2. Sluggish transmission.
3. Not as loud as you would like.
My advice to buyers.....
Its not a ///M car its for a different market. If your in that market I think these are a good buy. The 630i which I drove also is not appreciably slower but doesn't sound half as good. Manuals and SMG versions are available but rare. This is a muscle car......murica fuck yeah.