KOHALA COAST, HI – Toyota Motor Corp. is getting pretty good at this hybrid thing.

When consumers complained that the first-generation Prius hybrid/electric vehicle suffered from power surges during steady highway driving, engineers set out to smooth the delivery of torque – and largely succeeded.

When critics grumbled that hybrids still lacked punch, Toyota opted for more displacement in the form of a V-6 for its Lexus RX 400h and Toyota Highlander hybrid cross/utility vehicles.

The RX 400h is good (and sold 20,674 units in 2005 since its April arrival), but its delivery of torque from a standstill remains lacking. Move your foot from the brake pedal to the accelerator at a stop light, and the gasoline engine sputters back to life with an air of hesitation that undermines its luxury roots.

Lexus GS 450h.

In the Japanese spirit of continuous improvement, Toyota engineers have taken these concerns to heart and put them to rest with authority in the new Lexus GS 450h hybrid sport sedan.

The Honda Accord Hybrid distinguished itself as the first HEV that improved fuel economy while also boosting performance with an impressive 255 hp.

The GS 450h is a performance-oriented HEV, too, but it trumps the Accord Hybrid in grand style, catering to a well-heeled demographic that will have to cough up about twice the money for a car that Lexus says is as quick as a Porsche 911.

Let's look at that claim. The Porsche 911 comes in multiple configurations, and the coupe, with 6-speed manual transmission, darts to 60 mph (97 km/h) in 4.6 seconds. Other 911 models are nearly as fast.

The rear-wheel-drive 911 coupe with Tiptronic automatic transmission clocks in at 5.2 seconds, which is the same 0-60 time achieved by the GS 450h, according to Lexus.

The portly GS hybrid has a curb weight of 4,134 lbs. (1,875 kg), compared with 3,164 lbs. (1,435 kg) for the lithe 911 with Tiptronic. Clearly, pitting these diametrically opposed vehicles against one another is like suggesting Mike Tyson fight Sugar Ray Leonard.

Virtually no one will cross-shop a 911 with a GS 450h, so the comparison seems silly. But Lexus makes a valid point. Its sedan is practical, stylish and fuel-efficient, while being just as fast as a world-renowned high-performance European sport coupe.

No, the GS 450h does not sound like a 911 or leap with accelerative glee at the touch of the throttle.

But for a big sedan lugging 40 nickel-metal hydride battery modules, the GS hybrid is enormously gratifying to drive, remarkably well composed and impressively responsive in its own Lexus ultra-refined way.

During a media test drive here, Toyota Executive Engineer David Hermance declared the GS 450h "the best hybrid yet," and he challenged journalists to identify the point at which the engine kicks on during acceleration.

From a standstill, a permanent-magnet motor generator drives the rear wheels, and the 3.5L V-6 underhood springs to life at varying times, depending on the driver's level of motivation. The more forceful the pedal input, the more quickly the engine adds to the mix.

A second permanent-magnet motor acts as a primary generator, starts the engine and controls engine speed, but does not turn the wheels.

The electric portion of this latest iteration of Hybrid Synergy Drive should not, however, overshadow the vastly capable and all-new 3.5L DOHC V-6 (corporate designation 2GR-FSE), which debuted in the IS 350 sedan in 2005.

This advanced gasoline mill, which recently earned a Ward's 10 Best Engines award, has two injectors per cylinder (one port, one direct), as well as continuously variable valve timing with intelligence. (See related story: Toyota Motor Corp. 3.5L DOHC V-6)

Its only drawback is that it requires premium unleaded fuel.

Combined, the parallel hybrid system produces a whopping 339 hp, trumping the output of certain 911 models, by the way.

The GS 450h is enormously strong and, in accepting Hermance's challenge, journalists indeed struggle to detect when the V-6 was churning, or merely along for the ride.

Helping the cause is a continuously variable transmission, which Lexus says is the world's first longitudinal hybrid gearbox. It is so smooth it could make believers out of CVT critics. Likewise, the regenerative brakes afford stopping that is smooth and linear, unlike the grabby, ultra-sensitive stoppers onboard previous Toyota hybrids.

With the car's performance credentials cemented, it was time to study the GS 450h's fuel economy. Initially, it was awful, achieving a mere 18 mpg (13 L/100 km), according to the onboard computer, during moderately aggressive driving through winding, hilly roads.

With a tender foot, we achieved 24.4 mpg (9.6 L/100 km), which remains a far cry from the combined 28 mpg (8.3 L/100 km) Lexus says to expect in the GS 450h.

This is getting to be old hat – complaining that an HEV's fuel economy is not living up to its billing. If a car must be babied to come close to its rated 28 mpg, then what's the point of giving it 339 hp?

The thrill of a 911 is appreciating its accelerative means and applying them when prudent. Buyers of the GS 450h, filled with environmental guilt, will want fuel economy, not 911 titillation.

Lexus knows the market for this car will be small. The company plans to sell fewer than 2,000 in the U.S. and 6,000 worldwide annually.

Given its Toyota DNA, the GS 450h somehow will find an audience. In 2007, when Lexus will launch a V-8 hybrid version of its all-new LS flagship, Toyota expects to sell its 1 millionth HEV.

The GS 450h begins the era of hybrids with attitude – cars with expressive, sexy lines and even brute strength.

Pricing has not yet been set prior to its spring arrival in the U.S., but Lexus says the car likely will be more expensive than a V-8-powered GS 430, which has a base price of $51,375.

That sounds like a lot of money. But considering the RX 400h has a tag of $48,535, the GS 450h may be appropriately priced because its powertrain is superior and offers seamless acceleration and a vastly more satisfying driving experience.Â