From what I've read online, the LS600h has a 294kW/394hp/399PS ICE (the V8) and a 165kW/221hp/224PS electric motor (MG1 or MG2), but the combined power is "only" 327kW/439hp/445PS. I presume the combined power is lower than the sum of the two power plants due to them not producing peak power at the same time. Too bad; 600+ hp would've been good for bragging rights.

I was recently on a highway and encountered road works, which had a lowered speed limit. After the road works ended and normal speed limit was restored, I put up the kW display and floored it all the way from 50kph/31mph to 140kph/87mph. The power reading climbed all the time, finally reaching 297kW just as I hit 140kph.

Is the available power restricted at lower speeds or something, perhaps to preserve fuel economy and/or the drivetrain?