Some smoke on start up is normal. Some smoke in the rear view mirror is normal when you stomp on the throttle. Under regular driving, no. If you can't see the headlights behind you, something is wrong - either overfueled or leaking/burning oil.
A small change in your right foot can too. I've found that smoke is highly subjective. A small grey cloud is normal. A noticable black cloud might be overfueling by a tad or it mightbe normal. If the headlights behind you disappear by 75%, then you are definitely overfueling.The problem in this thread may be related to overfueling, your car may be the same. Even a small change in fueling can greatly increase or reduce the noticable smoke.