my friend has a 1.8turbo passat on idle it has alot of white smoke. it doesnt smell of burnt oil doesnt use oil or water no mixing of water and oil could it be the cat breaking up?. i havent drove the car so a cant say if its lost power but a dont think it has

 

Last time I had alot of white smoke on idle on a car it was the turbo. Drove fine just smoked like a steam train if you sat idling for any amount of time.

 

its as soon as you start it it smoke it looks like a cloud after a few mins of idle it clears then if you rev it just a wee puff of smoke nothin really. a thot a fuked turbo it be grey or black and a smell of burnt oil

 

Everyone says it should be blueish grey, but mine was more white. (black is normally fuel related) I think it was a mixture of high blowby pressurising the crankcase and forcing the oil past the turbo seal or something like that. It didn't smell of oil from what I can remember (this was 15years ago now) Mine didn't do it on start up though.
Could it be the valve stem seals/valve guides leaking?

 

Generally
White smoke=burning water
Blue=burning oil
Black=fuel

But, not always.