Perhaps it was a stuck thermostat.

On that crazy mileage, I have had similar experiences when driving real hard. Once last year when driving from Eau Claire WI to Thunder Bay Ontario I had a deadline was putting it to the floor 85-90mph with lots of passing on the two lane road between Duluth and Canada, 30mpg. another time was this past December, same situation Chattanooga TN to Hickory NC 85-90 29mpg on very hilly roads with long grades.

Oh I almost forgot. on the Canada trip I was running a veggy blend.

_________________
Manure green 2005 CRD sport4x4, GDE Hot tune, Cat Gut, OE skids, Draw tight hitch, Duramax lift pump, 160K on multiple varieties of fuel, XM radio, Escort live with Redline, fog light mod, GPS, Icom IC7000 all band radio call sign KC9QPF, Grabber AT2s on Soft 8s, FIA grill blanket.