Personal experience with my previous car, a Toyota LandCruiser HDJ100. My RX450h is one year old: no problems reported in 18.000 miles. One of my friend has a 10 years old RX300 with 190.000 miles: no problems reported too.
I buy RX450h in Luxury trim. Features are at top.
I drive about 10% traffic, 30% city, 20% suburban and 40% highway (75-80 mph). My driving is quite smooth. Fuel consumption is 28 MPG
299 horse power do their job when needed