Living in a hilly area, in my RX450h, I get on average 9l/100km city and 8.6l/100km on the highway.
Also, having previously owned a 2007 RX350, can confirm that the RX450h suffers from torque steer when accelerating hard. I believe the RX350 splits the drive roughly 50:50 between front and rear wheels, while the RX450h is primarily front wheel drive. Never had issues with hard acceleration with the RX350. Also, the electic motors puts on more torque faster, which doesn't help. Agree with Lexo, to date I have only noticed the torque steer kick in when turning (e.g pulling back into your lane as you complete overtaking a vehicle, or accelerating hard just prior to coming out of say, a right hand turn) not in straight line acceleration, which I have tried on the Monash freeway entrance ramps.