@sozobe,
When you relate that chart to the historical gas price chart it makes a lot of sense to me.
I was involved with the trucking industry for about a decade. When the prices really zoomed up, starting in late 2006, truckers really started to run into problems. Truck leases were given up, there was a surge in reports of stolen/burned trucks, smaller trucking firms went under, large ones laid off drivers ... things got nasty in the industry in the 3rd quarter of 2007 ... the balance of the economy seemed to follow along about 6 months behind. Truckers are like the canaries in the coal mine of the North American economy.