fMRI, Driving and the Samurai Radiologist

I'm following up, sort of, on my previous post on the limitations of the fMRI. I just found the Samurai Radiologist blog and he's got a post on a study using fMRI to measure the influence of talking on one's cell phone while driving. He says,

"Despite the title of the article, they did not study actual driving -- the sheer size of a decent fMRI scanner precludes this...'Participants steered a vehicle along a curving virtual road, either undisturbed or while listening to spoken sentences that they judged as true or false'   ...The dual task condition produced a significant deterioration in driving accuracy caused by the processing of the auditory sentences.' This conclusion is not exactly a bolt from the blue -- they cite a number of other studies that echo the same conclusion: your driving sucks when you use a cell phone, hands-free or not."

So there you have it. Another study that uses fMRI to measure brain activity while the subjects are inside a magnetic tube with whirling magnets (or whatever's in there) while they are doing  a simulated task -- this time driving and talking on the cell phone. Only there's no car, no cell phone (handheld nor hands free).  Whatever happened to controlling researcher interference?

I must state here that I haven't read the research report, so the researchers may address interference. But it seems that in their experiment, as interesting as it is, the brain is involved in a qualitatively different environment and that any generalization to a real car and driving down a real road would be somewhat suspect.