I have a Garmin 390 and have found the time is always less than on Tyre or MRA. I consistently ride at least 10 kmsh or mph over the posted speed, and think the Garmin has adjusted the time accordingly. My time to destination is always bang on when I get there.
Garmin use different maps and has a different routecalculation.
The driving time is an estimate time.
Thanks for telling.
Whose time should I trust, Tyre or Garmin?