An ambulance passed me this morning on Lakeshore.  A number of cars tried to draft behind him as he made his way.  It wasn't overly aggressive although a truck did gently cut one driver off as he got back in his lane.
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some amount of this is inevitable as drivers get back into the lane the ambulance used.  I rarely see it very aggressive with most drivers leaving some space behind the ambulance so others can get back in line.
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This morning I was in the furthest lane so could not have moved over.  It didn't matter - we came to a red light that the ambulance went through.  By the time it was green he was out of sight and traffic moved normally