My favourite app
I dont get to use it as much as I would like, it that has more to do with not doing enough track days.
Love that this app is scaleable. I started with Rookie and have since updated to Grand Prix. It works with just the iPhone out of the box with just the app, but can also be scaled up with external hardware as you get more addicted - cams, OBD2 sensors, better GPS trackers. All of which I have done and am impressed with the capabilities of just an app.
Support is awesome and it is continuously updated and features added, such as the new dyno function (which I think is free for GP only).
Ive used it for autocross, lapping days, karting. Even mountain biking. Have always been happy with it and have recommended it to several friends.
Maikeru73 about
Harry's LapTimer Rookie, v20.2