I work for a company which fitted trackers 3 years ago, all it has done is make the engineers drive slower to jobs and at the back end of the day instead of rushing a job and doing a job on the way home to get a good start for the next day, the engineers just take there time.It has shown up few d***heads,but if the service manager is doing his job he will still be able to catch these engineers out. We still get calls from the service dept asking where are you.