A study of psychomotor and cognitive function reaches this conclusion:
Patients receiving a stable dose of sublingual buprenorphine showed no significant impairment of complex psychomotor or cognitive performance as compared to healthy controls. However intake of illicit drugs as well as the lack of social reliability are major problems in this specific patients group. Despite of the absence of a relevant impact of the drug on driving ability, those patients do not seem to be qualified for getting their driving license.
The conclusion about the “intake of illicit drugs” appears to be based on the fact that over 60% of their suboxone maintained subjects tested positive for additional unreported drug use.