Phil: I wonder if we're seeing the slope of the Corolla graph getting less steep as speed increases to 120. That would be consistent with other graphs I've seen, eg:
( source: Speed kills: testing MPH vs. MPG in top gear - MetroMPG.com )
That graph suggests to me what we're seeing is the engine approaching the best BSFC zone as speed, load & RPM rise.
roflwaffle: I didn't really do a lot of driving in the car. I did a couple of mostly rural trips in cold weather (-5 to -10C) that netted mid 40's MPG (US). Left to his own devices, my dad's mileage was
22.4 mpg in wintertime 100% sub/urban driving (from:
http://ecomodder.com/forum/showthrea...rolla-546.html ). Not sure what he's getting on the open road.