Correlation between speed and cost efficiency

Group J has decided to research if there is a correlation between how fast the AEV goes and the cost. The group believes that the faster the AEV runs, the more cost efficient it is.  The group will run the AEV on the track multiple times at different power levels, and some of the trials will be completed with the caboose attached.

Current AEV Findings:

After the tests and observing the data, the group concluded that it is more efficient to run the AEV at a fast speed rather than a slower speed. The pros of running the AEV at a lower power allows it to brake more easily, but takes up more energy in turn using more money. With every test, when the AEV ran at a faster speed with or without the caboose, the AEV used less money.