Some notes on my test method for the July 15 2018 Velocity vs. Power Chart:
I have a stretch of road way that is newly paved and very flat near my house. On Sunday mornings there is very little traffic so I was able to do runs both directions on the road for 45 minutes with out problems of traffic interfering with my data collection.
Also, as it turns out we had perfect temperature 67-68 degrees and almost no wind.
I used my GPS to verify speeds and set speed control at a given speed. I would then watch Leafspy motor power until it stabilized and then watch for 3 to 4 more readings to take an observed average of the Leaf Spy motor power reading. I would record that for each speed going east and for each speed going west.
I then quickly removed the hubcaps and repeated the testing with no hubcaps.
The Ecomodder data was taken over a week of driving were we log all our parameters and basically my wife and I hypermile as best we can in the traffic / speeds for our normal commuting tasks. Our conclusion is that we could barely tell any difference in our Miles per kWh (even though we REALLY wanted the hubcaps to work). Of course there are lots of variables in daily driving like how much AC we were using and how much high speed verse low speed, blah, blah, blah...
If it were my car, I'd keep the caps on, but it's her car and it blends in better without the very noticeable hubcaps.
By the way, I found this flat road by studying the area around my house with www.flattestroute.com