doland

I was wondering how to use it when you're actually driving on the track. It seems like it would be cumbersome and inaccurate trying to press the button while you're actually focusing on driving. Not to mention the timing; you'd have to press STOP at the exact time you pass the end flag. Is it actually useful?

brendanf

I have tried it out and found that yes like you mentioned you have to time it yourself so there will be some variation.

It would have been nice if Lexus used the GPS signal so you could mark the finish line and have the system take care of the rest for you.

I ended up buying a RaceBox mini when they had their kick starter and use that instead now. Far more accurate and it measures more telemetry like accel, braking and corner g’s. It also includes hundreds of tracks from all over world.

LoSt180

I tried to use it on the track and found it worthless for the reasons you mentioned. Generally the start line is on the long straight, which is generally a good time to relax your hands and check your gauges. So in theory it's a good time to click lap counter. In reality, I'm not that precise if I even remembered, or in addition to checking the car you're pointing by passes or passing others.

I find the tire pressure gauge the most useful anyway. I got a suction cup mount for my phone and use the app Track Addict. It tracks laps using GPS automatically so I can use the straights to check temps and pressures and not timing a button press.