Lexus raises the SUV hybrid fuel-economy bar with its RX 450h hybrid SUV. The EPA has bestowed ratings of 32 city/28 highway for the front-wheel drive model and 30 city/28 highway for the all-wheel drive model, some 16 to 20 percent better than its predecessor, the RX 400h.
2010 Lexus RX 450hEnlarge Photo
Helping the new model achieve better mpg are a 3.5-liter Atkinson-cycle V-6, increased ability to drive in electric-only mode, lighter electric motors, and smaller batteries. Despite the added frugality, the RX 450h churns out more power than ever before, at 295 total system horsepower. Lexus claims performance "similar to V8s with better combined fuel economy than the average four-cylinder mid-size sedan."
Additional economy measures are the expected accessories driven by electric motors rather than the engine: power steering, water pump, and air conditioning. Unexpected is a new exhaust heat recovery system that transmits exhaust heat to engine coolant through an transfer unit installed in the exhaust stream aft of the catalytic converter. This system speeds engine warmup to promote earlier, more frequent, and longer engine shut-off periods.