這是有人的回答，哈哈

1) Some S62's burn oil because the rings do not seal well. Ring design was not optimal and this resulted in marginal oil control. This is not caused by valve stem seals or other sources. Ring tension is intentionally set to a bare "minimum" by engineers to minimize cylinder wear, minimize ring wear and minimize friction. Folks do not appreciate this fact. The engineers could easily have doubled the ring tension to cut oil usage by 10x, but engine lifecycle would suffer greatly. Oblivious folks would be delighted, however I would not. High oil consumption sometimes has pros and cons.

2) This phenomenon is quite common. Blowby and excess oil usage varies widely from cylinder to cylinder and from car-to-car. This has been the case for engines with marginal ring seal over the last 100 years. There are dozens of possible reasons and it varies from vehicle to vehicle. BMW M5 engineers clearly pushed the low tension ring concept a bit too far on the S62. Higher concumption may not have surfaced on test vehicles.