[chuckm]

Well, yes and no. To really gain a good understanding of your improvement, you need to test it under as near identical conditions as possible. With solar cells connected, make a short back-and-forth run on a road with no stop lights and little other traffic. Make the same run with the cells disconnected. Run the route yet again with the cells reconnected. Check results after each run.
It's difficult to compare results on runs such as yours. Is there an elevation difference? Difference in traffic loads? The idea is too eliminate as many variables as possible, otherwise your results are, statistically speaking, contaminated.