For the record, I was interviewed for a
hypermiling article in Edmonds. I was asked what was the edgiest hypermiling tatic and mentioned close drafting, then went on to stress I'm not endorsing it. Furthermore, the opprotunities it would increase fuel economy are limited. If the truck is not going at a steady speed that is at least somewhat moderate for a long distance - it's just not worth it. At least 95% of my driving is in the Dallas/Fort Worth area - the traffic just does not lend itself to this kind of driving.
Yes - it's risky....
but how often can it be done?
Hazardous driving happens a lot on the roads, but close drafting is relatively rare.
This topic is often a red herring to say all hypermiling is dangerous.