Despite the current mad rush for fuel-efficient vehicles, sales of the most popular hybrid car, the Toyota Prius, are unlikely to mushroom this year. In fact, most dealers in Toyota’s western region—encompassing California, Oregon, Washington, Nevada and Arizona—are out of stock. Customers should expect long waiting lists for the Prius, and in some cases, big dealer premiums, for the rest of 2008.

“Unless Toyota sends a lot more cars, we’re going to see Prius wait lists spin out again to about six months,” said Toby Parks, sales manager at Toyota of Berkeley, Calif., in an interview with HybridCars.com.

As recently as four weeks ago, Toyota of Berkeley had 60 Priuses on the lot and ready to sell. “We were offering $2,500 off on fully loaded Prius packages and the rest were selling for right around invoice.” Parks was even selling Priuses to customers from out of state that were unable to find the vehicle—which is rated at 48 mpg in the city and 45 on the highway.

Then, two things happened at almost the same time. First, gas prices soared well above $4 a gallon. Next, according to an inside company source, Toyota dramatically reduced production of the Prius sedan when it began retooling its production line for the 2009 model year. The new model is expected to be slightly bigger, faster and more efficient than the current version. In addition, company sources confirmed that Toyota is preparing to offer a wagon version of the Prius in either 2009 or 2010.

The crunch between high demand and diminishing supply is leaving Toyota dealerships in Northern California—one of the most popular regions for hybrid cars—with a current allocation of only about 400 Priuses to share among 65 stores. That equates to an average of approximately five Priuses per dealership per month.

Parks said, “If things don’t change, the current wait of 6 to 8 weeks will continue to grow. I would not be surprised to see buyers waiting as long as five to six month waiting list soon,” HybridCars.com’s “Price Pulse,” which allows hybrid buyers to report and track waiting lists across the country, shows a waiting period of 13 weeks in Fayetteville, Ark., 5 weeks in Germantown, Tenn., and 4 weeks in Newport News, Virginia. These waiting durations were common for much of 2005 and 2006, but subsided in 2007, when Toyota ramped up production and gas prices were relatively low.

Dealerships are responding to the shortage of Priuses with different strategies. Some wait for Priuses to arrive on the lot and then offer the vehicles on a first come, first serve basis to walk-in customers. This is typically when dealerships charge big premiums. Others dealers ask sales staff to keep individual lists of interested buyers, and begin making calls from that list as soon as vehicles arrive. These dealers are also prone to applying extra charges.

Finally, a number of dealerships use a chronological inventory management system with up-front deposits. In this way, the sales person can tell the customer more precisely when the Prius will arrive with specific information about the car including colors and option preferences. “Babysitting the order is a pain. And there’s lots of customer interaction,” said Parks. “But it’s the only equitable way to make the sale when the market heats up like this.”