Bruce

This latest Lexus pushes the envelope in a couple of ways. One, it’s the first production big-league luxury sedan to utilize a hybrid powertrain. And two, it’s the first Lexus to command a (gulp!) six-figure price tag, going toe-to-toe with V-8- and V-12-powered variants of the Mercedes S-Class and BMW 7 Series.

Is a hybrid necessarily better in this application? Well, it is smooth. One could almost say vibrationless when its 4-cam 32-valve 5.0-liter V-8 shuts off automatically at most every traffic light, and during very low-speed operation. Gas it (hmm, poor choice of verb) and as much as 389 bhp’s worth of internal-combustion power and up to 49 bhp from one of the Lexus’ two motor-generators feed through a two-stage planetary-gear continuously variable transmission, then a compactly designed Torsen center differential, and on to each axle with a normal 40/60 front/rear torque split.



Power for the hybrid system is supplied by a 240-cell pack of nickel/metal-hydride batteries with 288 nominal volts, stepped up to 650 volts DC, then converted to alternating current by an inverter to power the motor/generator units. Only one of these provides power to the wheels; the other functions as both a starter for the gasoline engine, and a generator that either recharges the battery pack or supplies drive current directly to the other motor. Interestingly, the battery pack (a vertically aligned slab behind the rear seats) is cooled by the rear a/c unit, and both motors and the inverter are liquid-cooled, serviced by a loop with its own dedicated radiator. The “motive” motor also serves for regenerative braking, partially recharging the battery with energy lost through heat in those “old-fashioned” friction braking systems. Of course, the LS has one of those too, with big vented rotors squeezed by 4-piston front and 2-piston rear calipers.

Phew! Lots of complexity here, yet nothing earth-shakingly different from the Lexus GS 450h. What’s remarkable is the detail refinement and how seamlessly it all works together. Get on the brakes and the regen and friction systems don’t get into a petty tug-of-war that results in lurchy stops and a grabby pedal feel; it’s smooth and progressive from any speed. At cruise, there’s not the surging we’ve seen in past applications as power is continuously routed and rerouted. And depending on how you set a console-mounted switch that alters throttle-valve opening (with Power, Hybrid and Snow positions), the LS 600h L either oozes off the line like warm honey, or goes into “holeshot” mode to stealthily slingshot past the unsuspecting Mustang.



Roll-on acceleration is both strong yet oddly calm at the same time, with the electric motor effectively spackling any depressions in the V-8’s torque curve, and then some. A sharp throttle input will send revs to the 4000–5000-rpm range, yet there’s none of the disconnected, motorboat feel of conventional CVTs paired with smaller-displacement engines. Kick the selector lever into the far left gate, and the CVT becomes an 8-speed sequential-shift transmission, with a forward push for upshifts and a rearward tug for downshifts.

Twist the Lexus’ leather- and wood-trimmed steering wheel, and the 2½-ton sedan responds more nimbly than something with 121.7 in. between its axles really should. Its multilink aluminum suspension uses air springs and shocks with electronically adjustable valving, so like the throttle profile, you can fine-tune its response through another switch with Sport and Comfort modes. We found with its stability system defeated, it could even be coaxed into a little drop-throttle rotation around the skidpad (posting 0.83g) and a no-excuses 63.6-mph run through our 700-ft. slalom.

Engage the stability control, and its micro-processor does all the standard things (reduction of power, braking individual wheel[s] to put the car back on its intended path) plus something more: Through the car’s electrically assisted variable-ratio steering rack, it commands minor front-wheel steering inputs. The steering feel itself offers a luxury-appropriate amount of feedback from the road, and the only time you sense the all-wheel drive (at least on dry pavement) is at full lock where what feels like a bit of CV joint lumpiness comes through.



While the LS 600h L tolerates being thrown around, it’s much more content doling out a luxurious ride and secure handling while soothing its occupants with highly polished wood and meticulously stitched leather. Of course, room inside is cavernous, the rear seating almost limousine-like, with the leather-wrapped dash, hourglass-shaped center-stack fascia and luminous gauges similar to — yet slightly evolved from — the previous LS. A prominent touch screen handles nav-system duties and most other climate/audio requests (thankfully backed up by “hard” buttons that are large and clearly labeled) and as you might expect, the 19-speaker, 450-watt Mark Levinson sound system is almost as good as sitting directly in the orchestra pit. Its hard drive (shared with the nav system) has storage space for as many as 2000 digital songs. XM satellite radio, naturally, is standard.

For comparsion I've included both data charts for the LS460 and LS600

LS600h
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LS460
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Hypersonic

Fascinating. I will look forward to seeing comparisons between this Lexus and the Hybrid S class although it is expected the S class's engine will be assisted by electric motors rather than being a full hybrid engine. Lexus were astute identifying the potential for hybrid engines at this end of the market -- while the Germans were preoccupied with their HP war.

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