I have just bought a 1995 5-series and am really happy with it. Its done about 100k miles and is immaculate. It runs really well with no smoke, knocks or unusual noises; however it does have a problem starting. I always wait for the glow plug warming light to go out before starting, but it still always takes 3 times (about 7-10 seconds each) before starting. Then as soon as it starts it runs perfectly. The only thing of note is that when it does start it throws out a little blue smoke - but it stops doing this immediately.
It is always parked on perfectly flat ground.
Anyone got any ideas? Would a new set of glow plugs help?