Can hybrid drivers get more smug?

They're so sleek. So clean. So forward-thinking.

And maybe my brain is addled by engine fumes, but they always seem to be in a better mood than most people.

You know who I'm talking about -- people who drive a Prius or something similarly awesome.

In South Carolina, discussions of raising the per-gallon gas tax about a nickel from its current level of about 16 cents have stirred all kinds of unhappiness.

Still, most people at the table say the shrinking revenue collected from the gas tax won't be enough to pay for the state's road repairs as more and more vehicles hurtle across the blacktop. In the short term, the 5 cents increase could yield an extra $150 million. In the long term, our revenue haul would be a lot smaller.

Our gas-tax policy appears to be colliding with our trend toward greener vehicles.

Is it fair to let alternative fuel motorists off the hook for maintaining the roadways that they use alongside conventional vehicles? Is there a more equitable - and enduring - user fee out there?

Or should we shear this particularly woolly revenue sheep before it goes extinct?

I asked Don Weaver. He's the president of the S.C. Association of Taxpayers and member of a state panel that's recommending a hike in the South Carolina gas tax. He's also a proud hybrid owner.

Most people think Don's Ford Fusion hybrid car is pretty cool.

It gets about 42 miles to the gallon and 650 miles to a tank.

But if South Carolina raises the gas tax a nickel per gallon, will traditional motorists still be amused if they must shoulder most of the expense?

"It's not necessarily a loophole," said Weaver.

"I'm still paying gas taxes," he added. "We still use gas in the vehicle. We're just not using as much."

In Weaver's view, more hybrid cars on the road could lower gas consumption and, in turn, actually lower prices at the pump for all.

The S.C. Taxation Realignment Commission is recommending the Legislature approve a gas tax increase from the current level of 16 cents per gallon to about 21 cents per gallon. The pump price per gallon is 16.75 cents in tax, including 0.75 cents worth of inspections and environmental fees.

But it's not considered a permanent fix. With the push for more alternative-energy vehicles, the money stream promises to sputter.

At least Palmetto State policy makers have the luxury of a little more time to sort out a long-term solution than coastal regions and key states like Texas and Michigan, which are leading the way.

"Historically, South Carolina and the Deep South have not been hybrid strongholds," said Brad Berman, editor of HybridCars.com.

But he said, in general, higher gas taxes will not only put more hybrids on the road but prompt all consumers to buy more fuel-efficient cars -- a mid-size sedan instead of a full-size SUV, a four-cylinder car instead of a V6.

The lumbering Hummer driver may go the way of the chain-smoker who balks at the higher tax on cigarettes and finally quits.

Before settling on a gas-tax hike, Weaver said the subcommittee looked at a separate sales tax for automotive products and other ways to target automobiles, such as raising the registration fee.

But the potential of the gas tax, he said, was "the 800-lb gorilla."

It dwarfed all other money-raising avenues.

South Carolina's gas tax raises about $500 million annually and ranks third-lowest in the nation, according to the subcommittee report.

Still, the limitations of the proposal were not lost on the three-man panel.

"Simply put, alternative fuel vehicles, and the normal wear and tear that results from them, as with any vehicle, needs to be accounted for," reads the subcommittee report, which recommends that lawmakers "begin planning accordingly."

If the Palmetto State raises the gas tax next year, it will have been nearly 25 since the last change.

Meanwhile, the U.S. Energy Information Administration's Annual Energy Outlook estimates that in another 25 years  -- by 2035 -- nearly half of all light-duty vehicles sold will be powered by alternative fuels or other new technologies.

The Electric Drive Transportation Association, an advocacy group, also says policy makers will have to take a new look at how transportation infrastructure is funded.

"As we move toward a national fleet of clean, efficient electric drive vehicles, we will need to revisit gas taxes as the best way to finance infrastructure," said the organization's vice president, Genevieve Cullen.

The S.C. Department of Transportation, too, is not cheerleading for a hike in the gas tax.

The agency provided the TRAC panel with information about the state's gas-tax revenues and how other states compare, but S.C. Transportation Secretary Buck Limehouse has not called for a per-gallon tax hike.

"He has never advocated that a tax increase is the best way to achieve our funding needs," said Peter Poore, transportation spokesman.

In a letter to TRAC members last year, Limehouse warned about the cross purposes of the green movement and the way South Carolina pays for its roadways.

"National policy is in conflict with the highway funding structure," he wrote.

"Congress is encouraging the use of alternative fuels and increasing emission standards. Since both the federal government and the state government here pay for the highways from fuel taxes, this green initiative ultimately hurts our revenue."

His conclusion: The only way to increase revenue is to put more cars on the road and burn more gas -- something that would strain the roadways and call for more repairs.