LAS VEGAS – With gasoline prices topping $4 a gallon in many parts of the country this summer, seemingly the last thing America needed was another V-8.

But Hyundai Motor America bucked the trend by launching its first V-8 in its first near-luxury rear-wheel-drive car, the Genesis sedan, in September, three months after the vehicle arrived first with a 3.8L V-6.

The gamble appears to have paid off, as John Krafcik, vice president-product development and strategic planning, tells Ward’s that demand for Genesis V-8s “has been 'eye-poppingly’ surprising.”

Hyundai anticipated a 20% V-8 sales mix, “but indications from free-market demand seem to be more like 30% to 40% V-8. That’s where the interest is now,” Krafcik says in an interview here at the Specialty Equipment Market Assn. show.

When a new product launches, the buzz tends to spark a sales mix that is richer than the long-term, “steady-state mix,” Krafcik says, adding that many dealers still have yet to receive their first V-8 Genesis. “It’s early. We have to figure out how much of this is typical.”

But the early adopters appear to want the Genesis with all the bells and whistles.

“A lot of people were waiting for the V-8, because that’s what a lot of buff magazines have been driving and there has been a lot of positive coverage on the V-8,” Krafcik says. “People seem to want the most fully equipped car.”

So far, the V-8 “tech package” carries the highest mix, between 30% and 40%, based on how consumers are ordering their vehicles. “That’s a $42,000 car – the most-expensive Hyundai,” he says.

The V-8 carries a $2,000 premium over a comparably equipped V-6, and that package includes beefier brakes, better leather and other trim upgrades.

Hyundai has sold more than 4,000 Genesis sedans since June, and the auto maker should hit its target of about 6,000 deliveries this year, Krafcik says.

The Genesis coupe, offering a V-6 and turbocharged 4-cyl., arrives in March or April. Hyundai still hopes to sell about 20,000 Genesis sedans and 20,000 Genesis coupes in 2009.

The Tau 4.6L DOHC V-8 produces 375 hp and is reasonably economical, rated at 17/25 mpg (13.8-9.4 L/100 km) in city/highway driving.

That engine might become more efficient in the coming years as Hyundai considers adding cylinder deactivation and direct gasoline injection, Krafcik says.

Here at SEMA, Hyundai unveils the RKSport Genesis sedan concept, powered by a supercharged version of the Tau that produces 460 hp and employs cylinder deactivation.

Despite the prodigious thrust, Hyundai says the boosted V-8 in the concept achieves 18/27 mpg (13-8.7 L/100 km), which is identical to the normally aspirated 3.8L V-6 in the Genesis.

It’s too early to say when this cylinder-deactivation technology will find its way onto the production Tau V-8, says John Juriga, director-powertrain at the Hyundai-Kia America Technical Center in Superior Township, MI.

But when it arrives, Juriga suggests the production engine also could employ DGI and will achieve the same 18/27 mpg as the concept.

“We have direct-injection development work ongoing right now and cylinder-deactivation work ongoing right now,” he says. “Whether they’re coming together or not, we’re not saying. But the potential is definitely there.”

Hyundai’s system has a clutch that allows the supercharger to be deactivated at idle and during steady-state driving in 4-cyl. mode, further enhancing fuel economy. Juriga says the supercharger would be activated at about 1,200 rpm, up until about 3,000 rpm.

His preference is for cylinder deactivation and DGI to be standard on the Tau, rather than a special version of the engine, to streamline manufacturing.

As for a supercharged version of the Tau in production form, Juriga is less committal, particularly with wildly fluctuating fuel prices. “Right now the cost of fuel has dropped, but it’s expected to go back up,” he says. “Will we do it? It’s not going to be my call.”

Krafcik also says cylinder deactivation could be a possible addition to the V-6 in the future.

Advanced powertrains figure prominently in Hyundai’s plans to meet the U.S. corporate average fuel economy mandate of 35 mpg (6.7 L/100 km) in 2015 – five years earlier than required.

Even if V-8 Genesis sales remain strong, Krafcik says he is confident Hyundai’s CAFE average will not be negatively impacted, meaning the auto maker still should be able to hit the target by 2015.

“Our powertrain plan to 2015 and beyond is an amazing thing, with a much higher mix of 4-cyl. engines,” he says.

Some of those launches next fall include a face-lifted Santa Fe cross/utility vehicle, in which a 4-cyl. engine replaces the current V-6 as standard, and next-generation Tucson CUV, which will be available only with 4-cyl. power after offering an optional V-6 in the current model, Krafcik says.

Also on the horizon within three years is a new 1.6L I-4 in a front-wheel-drive sporty coupe that slots in below the Genesis 2-door, he says, adding that a turbocharged variant and DGI are possible additions for the diminutive engine.

In addition to the RK Sport Genesis concept, Hyundai unveils at SEMA its Rhys Millen Racing version of the Genesis Coupe, powered by a turbocharged 2.0L I-4 and sporting numerous upgrades, such as an 8-point roll cage and carbon-fiber body kit and wing.

tmurphy@wardsauto.com