Went on a 140 mile trip today. Took loads of measurements at different intervals. These are the results of my trip. 2001 v6 with new Pirelli Scorpion STR 215R65/16 98H tyres. Short story is:
120 miles at 60mph + 20miles mixed speed of 30/40/50mph (some at beginning, middle and end of trip).
8 = ambient temp
10 = average road temp
22 = max rear tyre temp
23 = max front tyre temp
41 = max vcu temp (measured circumference side of vcu) (7.8 at start)
46 = max rear diff temp (measured underside outer case) (7.8 at start)
75 = max ird temp (measured ird filler plug)
All values in degrees. I got 28mpg.