Well, I can't really explain why it's included on the 300h, but I guess Lexus thought it would be "cool."
From Lexus: The NX 300h F Sport features Lexus’s first G-force sensors – the G-Monitor – which send live data to the multi-information display. The G-Monitor screen shows a G-ball moving in line with the lateral and longitudinal forces on the vehicle, giving the peak force experienced in each direction.
For 24 years of my life I pulled up to 9 g's for a living, but I never had an accelerometer that I would look at while doing so....it was just something to glance at after a maneuver to insure you hadn't over g'd the airplane. I doubt you'll be speeding around corners while checking how many transverse or lateral g's you are attaining, and I don't think you will have a problem over g-ing your 300h unless you hit a wall while traveling at high speed. In any case, IMHO, the G-Monitor in your car is much like the sound generator that bolsters engine noise....silly!
