Driver variable is what I was pointing out. Most of the cars on the list were driven by Randy Pobst for Motor Trend or TireRack.com.
For comparing cars laptimes, we want as many variables as possible to be the same, which is why I was only comparing times from other cars driven by Randy Pobst.
The driver variable is huge, I doubt many of us could even be within 10-seconds of Randy Pobst times. He was able to record near identical back-to-back 2015 Mustang GT laptimes, so I would say he's able to extract near max potential from every car he tests.