Hybrid has become a recognized term, but the exact definition is far less familiar.

For many, a hybrid-electric vehicle is a cool, environmentally correct vehicle that carries beautiful people to the red carpet on Oscar night.

And it is synonymous with fuel efficiency at a time of escalating gasoline prices.

But the term hybrid refers to a growing proliferation of powertrain technologies. Customers find themselves choosing between models of vastly different pricepoints, degrees of technology and potential fuel savings or performance gains.

Take the Saturn Vue cross/utility vehicle, which eventually will be offered with a choice of a conventional gasoline engine or three different hybrid systems.

For an extra $1,800, a buyer can get an entry-level Vue Green Line, a mild hybrid that shuts off the engine when the vehicle stops and restarts when the brake pedal is released. It cannot run on electric power alone.

Then there is the “full hybrid” Vue in the works with General Motors’ Two-Mode System that incorporates electric motors in the automatic transmission. When the ’09 Vue with Two-Mode bows, the technology easily could tack $5,000 to the sticker.

Also on the horizon is a plug-in hybrid Vue, allowing consumers to plug into an electrical outlet to recharge the batteries. It is anyone’s guess as to what it will cost to add a substantial battery pack to the already expensive Two-Mode System.

And that’s just GM.

Toyota is quick to point out the differences in its full-hybrid system, as is Ford. Nissan is dipping its toe in the water with the ’07 Altima equipped with Toyota’s Hybrid Synergy Drive technology.

Many forecasters expect hybrid sales to peak in the next five years with as many as 15 new vehicles. U.S. buyers could have 25 or more models to choose from by the ’09 model year – covering a huge price range and offering a wide spectrum of efficiency gains.

It’s a free-for-all, with no regulated definition as to what constitutes a hybrid.

The industry appears split as to whether this is a good or bad thing.

Nissan’s Thomas Lane, who oversees product planning, says the auto maker does not want to over-promise the benefits of hybrids and leave consumers disappointed or jaded.

“If it’s just window dressing and a sticker on the back of the car and nothing really happens, it’s not fair to the customer,” he says, and it won’t take long for buyers to get wise.

Other auto makers express concern that creating confusion for the customer is always risky.

Then there are those who share the opinion of GM Vice Chairman Bob Lutz that the more choice the better.

And it all will be moot, he says, when ultimately all cars have only electric motors.

But the potential for backlash in the interim is real.

Dealers will bear the brunt of consumer wrath if buying a hybrid is as daunting as choosing a new cell-phone plan – and the cost vs. savings ratio in the end falls short of expectation.