My 2wd saff is smoking at the moment aswell, it only does it when i let the car slow down with the gears, then accelerate, a few people have said it may be my turbo or my valve stem oil seals, so i got my turbo ckecked and its fine, im now going to get the seals done, i dont no if yours is quite like that but i would get both looked at. hope this helps at least a little