Nervous drivers are more likely to make mistakes, according to the RAC, which ups the ante even more. It helps explain "middle laners" - those disenfranchised motorists who cling to the belief that as long as they stay out of the "slow lane" they at least have some stake in the motorway social hierarchy.
Then again, I saw one guy last week barreling along at 70 mph in the middle lane and I was the only other car within a half-mile of either direction. Even more, he had his left-indicator going all the time. I think he'd achieved an advanced state of nirvana more normally found after a Camberwell Carrot and an audience with the Maharishi Mahesh Yogi and was utterly closed to external stimuli.
1) Note for Americans and other aliens2: the inside lane is the one furthest away from the central divider between the two directions of traffic. That is, if you were to take a Freeway, mark the six lanes from left to right ABCDEF, then swap the two sides over so they were DEFABC, lanes C and D are still the inside lane.
2) Yes, I stole that from Terry Pratchett/Neil Gaiman. And the footnotes on footnotes too.