Mr McMahon says that when the system was introduced 18 months ago, 90 per cent of the company's 1100 Auckland drivers were recorded as being in the red more than twice a week.
Now, as few as about 20 drivers a week are still seeing red, amid rivalry between various bus depots to produce the lowest number of transgressions in the fleet.
The system is endorsed by the Tramways Union, especially given the company's assurance that only "critical" speeding offences will generally incur disciplinary action, and Mr Pettigrew says it provides benefits to both himself and his passengers.
When he joined the company almost three years ago from a background of office work, he wondered if he could handle the stress of driving through Auckland's congested traffic, especially as he was a diabetic and had been on medication for about 20 years for high blood pressure.
"I didn't think I could survive," he recalls. "But fortunately for me, when telematics was introduced, I really understood that not only was it taking care of the bus but simultaneously it was actually taking care of the drivers.
"It was encouraging the drivers to drive carefully, drive slower - as a result of that, stress levels dropped dramatically."
So much so that he no longer has to take his tablets, and his doctor says his blood pressure "is just like a teenager's".
Mr Pettigrew generally clocks up 11 trips a day, predominantly between Britomart and Glen Innes or Panmure, working the night shift from 2.45pm to 12.45am.
That includes school runs during term time, which provide their own challenges.
"They can be choir-boys, they can get boisterous, but they're boys and I certainly understand that," he says.
He usually works for five hours before taking an hour-long break, and unless held up in traffic has a few minutes between trips to stretch his legs or nibble on snacks to maintain energy levels. Mathew Dearnaley