The New Lexus RX450h Hybrid SUV

Fans of hybrid SUVs have a new model from Lexus to consider. The premium carmaker debuted its all-new 2010 RX450h hybrid crossover at the 2008 Los Angeles International Auto Show last week. The 450h replaces for the brand’s current generation RX400h SUV, which was on the market for only two model years. The new 450h is based on the completely redesigned RX line, which boasts sharper styling, greater performance, and a reconfiguration of interior space.

The second generation RX hybrid will also be powered by Toyota’s proven Hybrid Synergy Drive system, utilizing a new Atkinson cycle 3.5-liter V6 engine. With this larger powerplant, output will be 295 horsepower—27 horses more than the current RX400h. The new model will retain the electronically-controlled Continuously Variable Transmission of the current model.

In an effort to improve efficiency, two new technologies have been implemented within the hybrid system. One is an exhaust-heat recovery system, which lessens the time it takes for the engine to warm up. This allows the engine to stop more frequently and for longer durations of time during vehicle operation, thus improving fuel economy and reducing emissions. The other innovation is a cooled exhaust-gas recirculation system. This feature boosts fuel economy by reducing engine pumping losses. Toyota has not said how much of an actual improvement in efficiency these two systems garner.

The RX450h is available in both two-wheel drive and all-wheel drive versions. But since most all-wheel drive vehicles compromise efficiency due to the extra weight from mechanical components, Lexus has taken steps to offset this issue. To that end, the RX450h utilizes a rear-mounted electric motor-generator, which will enable all four wheels to simultaneously engage in regenerative braking. The result is a more efficient process of recapturing energy.

Aside from hybrid system advancements, the new RX450h will share most of the technological and luxury enhancements of the new non-hybrid RX350. The Lexus RX450h will go on sale in Spring 2009.