My 2006 e65 leaves white smoke somtimes

White smoke isn't really smoke, it's steam and a sign of burning water.

Head Gasket Failure or some reason to
dump coolant when hot, out the exhaust

Mr.Fatodu,
according to your statement, your car is using enough engine oil. Now this depends to how often you were changing the engine oil and the guality of oil used. For me all BMW'S OIL CHANGE Every 5000 miles long drive and 4000 miles short drive. Oil used full synthetic Castrol 5W40. Since now you have the smoking issue should use an oil treatment additive FORTE For stop smoke. Trythis first and see whether you have any success.

Run it for awhile then decide, still smoking after that and smoke smells sweet it is coolant.

This widespread problem is the one part no one thinks of: ENGINE VACUUM PUMP.it runs mechanically off camshaft;once seal leaks,oil from camshaft housing enters vac oump and becomes ingested by engine,therefore exiting tailpipe,water accumulation in by product of catalytic converter changing smog/carbon to water/vapor.REPLACE VAC PUMP AND SEAL ,SMOKE WILL STOP!!!!

Sounds like you have a bad valve seal (or maybe several).

Basically there are seals for your valves that keep oil from dripping down into your pistons and smoking like crazy. When these go out, oil drips down when the car sits still for a while.

It's an intermittent problem because not all of your valve seals are bad. Depending on the position of your engine when you turn it off determines whether or not your bad valve seal(s) is going to leak oil into your piston.

I had this problem on one of my first pickup trucks. From everything that people told me, you don't really have to worry about it. It's embarassing, but it's not causing any real problems.

To confirm that this is the case, you could pull your spark plugs. 1 or more (but not all) should be fairly black and even have a little bit of gunk on it (maybe like a bbq grill).

I hope this helps.

White smoke or steam? If it's smoke, I bet you have an automatic transmission, trans fluid makes white smoke. There is a vacuum line from the trans to engine somewhere, there is probably a diaphragm that's broken. call your local trans shop it shouldn't be a huge expense to fix.
please leave a fixya rating if I'm correct

Sounds like a head gasket it could be your transmission depending on how dark you smoke is so
Grey=Transmission
White=Head Gasket

Do me a favor, check you radiator fluid level. Tell me if it is low. If it is.....I hate to say it, but you may have a blown head gasket or a cracked head. You are getting coolant into the combustion chambers.....

Its not the gas. I had the same problem. Its your crank sensor. It costs 50$ from the dealer.