These guys often run with faster cars to be able to observe the test car from different angles at different points on the track. It also gives the driver of the test car more drive (excuse the pun) to be able to chase a faster car and push the test car to it's limits. It wouldn't have done them much good to have gone around in the SRT6 with a Neon. These are not time trials where they just sit on the sideline and click a stopwatch.