Supersize trucks are selling so well that Nissan has a new version of its Titan King Cab, with an 8-foot cargo bed.

As gasoline prices go up, sales of gas guzzlers go down... right?

Apparently not, if you're talking about big pickup trucks. Though sales of some pickups seem to be stalling as gas prices increase, sales of the biggest pickups seem to be heading toward record levels. In fact, the bigger a pickup is, the heavier it is and the pricier it is, the better it seems to be selling.

Take General Motors, which reported halfway through 2007 that it had an inventory backlog of more than 700,000 unsold Chevrolet and GMC pickups. Despite that, there was only a few days' supply of its biggest models, such as the LT3 long-bed Crew Cab 4x4, which starts at $36,515.

Toyota is attempting to break into the full-size-pickup market with its redesigned and greatly enlarged Tundra. Toyota said it was hoping to top 200,000 units in first-year sales. The Tundra is offered in regular cab, extended cab, double cab and an especially huge CrewMax.

Sales at the low end of the product lineup needed incentives like 0 percent financing to juice sales. But Toyota said it was shocked to find that sales of the CrewMax were "way beyond expectations" -- no incentives needed. So production was shifted at Toyota's new San Antonio plant away from the smallest, regular-cab models to more CrewMax models. Still, Toyota said CrewMax demand was outstripping supply. So, Toyota said it would not only consider shifting more production toward its largest pickups but also study new variations, trim lines and model offerings in the market's high end.

Sales of Ford's F-150, the perennial bestselling vehicle in the United States, are expected to drop about 10 percent from the 800,000 or so sold in 2006 (a record 940,000 were sold in 2004). But there is no drop-off at the high end of the market. In fact, the top-of-the-line Harley-Davidson SuperCrew is back-ordered in some areas of the country, despite its $39,355 base price.

Sales also are reported to be brisk for the King Ranch trim package, also at the top of the F-150 line. And those are the vehicles that get about 13 miles per gallon in the city on premium fuel.

Ford said it conducted research into what was driving the pickup market. It found that "buyers want maximum luxury, V-8 power, ultra-sport, uncompromised utility."

Nissan found pretty much the same thing when it asked potential buyers what was lacking in the company's Titan line of big pickups. The one thing shoppers wanted that the Titan did not offer was a long cargo bed with its King Cab models. So a version with an 8-foot bed is offered for the 2008 model year. Nissan says the Titan King Cab now offers the biggest cargo box in its class.

Dodge is said to be studying an 8-foot bed for its massive Mega Cab models. Currently the popular Mega Cab is hampered somewhat by offering a 6.3 foot bed. When creating the Mega Cab, Dodge whacked a foot and a half out of the bed and lengthened the cab by a cooresponding amount. It's selling well despite the bed limitations, fuel economy in the low teens, and a sticker price that starts at $40,540.

All these top-line trucks can push $50,000 with options. But they are far from the most expensive models on the market. Ford, Chevrolet, GMC and Dodge all offer large heavy-duty trucks that, while they sell in smaller volumes, do more, cost more, and sell well, regardless of gas prices. Models such as Dodge's Ram 2500 and 3500, especially those with Cummins diesel engines, have almost a cult following.

Then there are the luxury liners of the industry. Lincoln, which a few years ago tried its now-discontinued $52,000 Blackwood pickup, is back with an F-150-based LT model that has a base price of $41,495.

But at this end of the market, lowering the price doesn't necessarily translate to increased sales. A case in point: Cadillac's Escalada EXT keeps going up in price, setting records for what can be charged for a pickup. The EXT now starts at $53,975 and can easily top $60,000 fully loaded. But buyers, Cadillac says, "can't get enough of 'em."