The University of Virginia has an interesting ongoing study in the works that will examine the effects of ADHD medications on real world distractions. The concern of the authors is that current clinical studies on the inhibition of distractibility with ADHD medications are based on highly controlled settings, and thus may not translate well to the real world.
Given the high rate of auto accidents within the young adult ADHD population the current study uses car mounted cameras to examine the effectiveness of stimulant usage. One interesting previous study they note found that manual shift cars actually decreased the incidents for students compared to automatics. My guess is that the act of having to shift requires the subject to frequently be reengaged into the driving process. An interesting result.
If you would like to follow the study you can find some information HERE and HERE.