We just did a similar experiment in the classroom: record position as a function of time. Go to the web page:
http://www.american.edu/IRVINE/bardhyl/DimKin3.htm and observe the motion of the 2 cars.

1) Which car goes faster?
 

2) Can you tell which car goes faster only by looking at the graph?

3) Obtain from the graph the velocity of the blue car and of the red car. (Remember the definition of velocity and build a table with their positions and times.)