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We just returned from a day in northern California testdriving the new Lexus RX 450h, and as you might expect, it's a rolling encyclopedia of new-car tech. We'll do our best to explain it all in thumbnails, but suffice to say, it's a capable and civilized alternative to your run-of-the-mill crossover rigs.
The heart of the RX is the time-proven Toyota 2GR 3.5L V-6 (a variant of which Lotus will be using next year on its GT4 Supersport race cars), which has been refined for this application with the addition of an EGR system for improved emissions and cooling, and an exhaust heat recovery system to aid in quicker heat-up times (i.e., cold-start conditions). The motor also runs an Atkinson-style combustion cycle (the power stroke is longer than the compression stroke), which helps to achieve greater fuel economy and thermal efficiencies at the expense of horsepower. How to remedy? In the RX's case, two ways.
First, the gas engine works in concert with Lexus Hybrid Drive, a battery-actuated hybrid system similar to Toyota's (Prius) Hybrid Synergy Drive. The Lexus system can be run for brief periods at high speeds as well as at idle (and during braking) to provide an extra power boost as needed, such as on steep inclines or for passing. In the new RX application, the battery can provide an extra 50 horses to the V-6's 245, resulting in 295 peak hp at 6,200 rpm. Second, the engine is mated to an electronic CVT transmission. We're not too keen on these "pointless" gearboxes, but we do know that they have fewer internals to break, are less expensive than a conventional slushbox, and can keep an engine revving in its "sweet spot" longer than fixed-gear transmissions. Add everything up and you arrive at an EPA-estimated 26 mpg on the highway, 28 city, from a V-6 powertrain that is amply powerful, frugal, and super-clean (SULEV-rated) in operation.
Read More at FourWheeler.com
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