The original RX400h debuted in 2005. The second-generation 2010 RX 450h introduces an updated version of Lexus Hybrid Drive, featuring a 3.5-liter V6 Atkinson-cycle engine, lighter electric motors, a smaller and lighter power-control unit and other fuel-saving innovations. With an EPA-estimated 32 mpg city and 28 mpg highway (30 mpg combined)—30 mpg city, 28 mpg highway (29 mpg combined) for the AWD—it earns 16-20% better fuel economy than its predecessor.

While achieving improved fuel economy, the new RX450h produces 295 total system horsepower, 27 more than the current generation RX400h. It will achieve Super Ultra Low Emission Vehicle (SULEV) certification in California (Tier 2-Bin 3 in other states), producing nearly 70% fewer smog-forming emissions than conventionally powered vehicles.