I've hypothesized that I might achieve better gas mileage if put the car in sport mode but drove frugally. My reasoning is that the sport mode defaults to higher regenerative braking. So far my only idea on how to test it is with one take full in economy mode and one tank full in sport mode hoping that the conditions were similar enough between the tanks to yield real data. But, I happen to be taking a long drive from San Francisco to Des Moines and I know that there are flat places along the drive to test. My first opportunity was from Ferley, NV to Wendover, NV. No drafting other cars and temperature was between 20 and 30 degrees F. I drove 50 miles in economy mode at 85mph with ACC on and got 30.9mpg. I then realized that the whole premise of my test was that the higher regeneration setting was going to yield better gas mileage. I'm never braking. But I could not stop there. 50 miles in normal mode and I got 30.8 mpg. No change as my modified hypothesis suspected. Last, 50 miles in sport mode. Problem is that 20 miles into the test, I arrived at Winnemucca and the speed limit dropped to 75, I slowed to 80. Bugger, this is probably going to tip my test to favor sport mode. Then the last 3 miles of my 50 test I started climbing a hill outside Winnemucca. I averaged 29.8MPG. You can see my power output was significantly higher due to the hill climb. Nebraska is coming up tomorrow.