If you know how to drive its not difficult to get consistent times in a stick shift car. Once I got the launch of my CL-S6 figured out I was running 14.55-14.62 every time down, like 4 passes in a row. My Mustang ran a string of 7 passes ranging from 14.06-14.15, all at the same mph. If you shift the same each time down and the launch is not a problem its not hard to be consistent. Bogging/and or spinning definitely will hurt consistency.

And a poor driver in an automatic will make it inconsistent also. At the most recent bracket racing event I beat 2 automatic tranny opponents and a very fast Z06 (stock, but still damn fast ).