I saw these push/pull scales and thought of a use case...measure a Greenpower car's rolling resistance.
You could take an initial measurement to establish a baseline and then make changes, such as:
1. tweak the front wheel toe-in, and remeasure to see if rolling resistance was reduced.
2. evaluate the effect of having too much tension in the sprocket chain
3. evaluate different wheel bearings, wheel bearing grease, tire compounds/pressures, etc.
These are some examples of the frictional forces opposing the vehicles motion and if you can reduce or eliminate them, you have conserved energy (the battery), and can power the motor for a longer period of time!
Check them out here.