How green is my hybrid

(Fortune Magazine) -- For years now, car buyers have been presented with a stark choice: Go green (do good), or go upscale (feel good). That all changes this summer when Lexus finally debuts its much-anticipated LS 600h L, the highest-performance luxury hybrid on the market. Deborah Meyer, vice president of marketing for Lexus, says the company is "shocked" that no other automaker has launched a high-end hybrid yet, given that "Americans don't want to give up horsepower or comfort."

How right she is, and how well Lexus knows its target buyers: affluent American enviro-conscious consumers who want to brag that their vehicle is "green" (even if gas mileage leaves something to be desired - more on that in a minute) but don't want to forgo the space, comfy interior or bells and whistles of a luxury car. And please, this crowd quietly begs, let the thing run on regular old gas, not hard-to-find alternative fuels.

The new LS 600h L

More from Fortune

Will Mmmhops be a hit? NBA confirms L.A. Clippers sale to ex-Microsoft CEO Steve Ballmer FBI and SEC probe into Carl Icahn and golfer Phil Mickelson

FORTUNE 500 Current Issue Subscribe to Fortune

Photo Gallery See more photos

Unlike its utilitarian cousin, the Prius, the LS 600h L (if emissions can be pared down, can't the name be too?) is laden with creature comforts, technology and gizmos. Some of the many highlights: It's a SULEV (super-ultra-low-emission vehicle) powered by a five-liter V-8 coupled with a high-output electric motor. The mating of the two produces 438 horsepower and a 5.5-second 0-to-60 time - impressive for a 5,000-pound sedan.

Those numbers are in the ballpark of its nongreen 12-cylinder adversaries from BMW, Mercedes and Audi and match the fuel efficiency of an all-wheel-drive V-6 - and yet the 600h L is 67 percent cleaner than its cleanest competition, the Mercedes S600 Bi-T, a ULEV.

There's an EV (electric vehicle) mode for quiet operation for three minutes max at speeds under ten mph. (Lexus says it's for navigating a parking structure fume-free, but it's otherwise known as the sneak-into-the-garage-late switch.)

A driver-monitor function sets off an alarm when the driver's eyes are off the road and it senses a potential collision ahead. The whole enchilada is outfitted with semi-aniline leather (less heavily dyed), an Alcantara headliner, and a 450-watt, 19-speaker Mark Levinson sound system. That's about a quarter of the highlights.

I went to Toyota's (Charts) supersecret test track in Arizona to drive this technological smorgasbord. Lapping on the ten-mile oval, I felt the LS's strong acceleration. As seductive as a W-12 Audi A8L? No, but impressive. The car is designed to make you feel perfectly in control, no matter what. The steering is precise at speed, there is little dive in the braking, and the electronic stabilizing system doesn't allow for tire-squealing in corners (bummer).

Three different air suspension modes allowed me to rattle my teeth, bump a bit or glide over without much intrusion on my inner peace. The car practically went to sleep on the 120-mph straightaways. At the end it occurred to me that Lexus has built its ultimate character statement: a high-end sedan that uses ultra-engineering to shield the pilot from the experience of driving. To most LS buyers, that will probably be seen as a plus.

The good news here is that Lexus has achieved a new level of luxury with this LS. All the right touch points work: The seats are fabulous, and there are dozens of buttons that allow you to adjust them until you agree. The back seats are equally roomy - how often do you hear that these days? And the touchscreen controls are intuitive and easy to figure out - another description you don't read often.

Now the bad news. The car achieved an average of only 17 miles per gallon during my test period - better than the BMW 760's 14 city, but that's splitting a hair. Other lows: I never got the electric-vehicle mode to work. It apparently needs a certain level of charge to function that I must not have attained; so much for sneaking in late. And an incredibly distracting moving hybrid graphic runs continuously on the dash, showing you whether you're in regenerative, economy, or gas-guzzling mode.

All in all, Lexus has put an elegant car on the road that will appeal to a wealthy buyer with a conscience. It isn't the purest enviro-statement out there (maybe that is why Lexus has chosen to make its "hybrid" badges glow blue) or the most over-the-top-posh limo. But it should be the darling of the eco-wealthy set - until those superclean, superfast European diesels start arriving in '08.