How to Standardize/Normalize three sets of test data of different lengths
Here is one idea.

First plot the time vs distance. These lines would have different slopes between the measurement periods and you would essentially estimate the speed between measurements. Here is a graph with one measurement window:



Since they're racing on the same track, the total distance driven should be approximately equal. You might need to stretch or shrink the height of lines to make sure they travel the same distance. (This might not be a good assumption for your case.)
Now, go from the y-axis and for regular distance intervals, look up the slope of the graph.
Then plot the observed estimated speed for each distance period. You'll end up with speed measurements at regular distances which will now have the same length of samples.

This way you'll have a fairly good approximation of the speed at which racers traveled at specific parts of the track. I.e. you can compare cornering speed etc.