DETROIT — Hybrid gas-electric vehicles are the current champions of fuel economy, and are getting snapped up faster than they can be cranked out, according to WestStart-CALSTART. But according to the "Auto Tech" column of Wired magazine, auto manufacturers are making tracks to produce diesel hybrids that will go even further on a gallon of fuel. Hybrid vehicles like the Toyota Prius, Honda Civic Hybrid, and Ford Escape Hybrid employ an electric motor that assists the engine and sometimes provides low-speed solo power, enabling the vehicles to go between 15 and 50 percent further on a tank than a comparable gasoline vehicle. Vehicles with diesel engines typically get 25 to 30 percent more miles to the gallon than their gasoline counterparts, according to Charlie Freese, executive engineering director at GM Powertrain. So a new generation of hybrid diesel prototypes being developed by General Motors, DaimlerChrysler, and Ford could soon surpass these milestones. In addition to increasing fuel economy, coupling an electric motor with a diesel engine can help automakers meet increasingly stringent emissions standards, according to Dan Benjamin, an analyst at ABI Research. Diesel hybrid technology has been used in large vehicles that transport heavy loads, including buses and locomotives. Earlier this year, GM unveiled the Opel Astra Diesel Hybrid, a sedan concept vehicle the company claims would increase fuel economy by 25 percent over a comparable diesel car, or approximately 59 miles per gallon. The vehicle uses a hybrid system with two electric motors being co-developed with DaimlerChrysler, according to GM. DaimlerChrysler produced 100 Dodge Ram hybrid electric vehicle diesel pickup trucks in December, according to spokesman Cole Quinnell. DaimlerChrysler's future diesel hybrids will be based on the hybrid technology being developed with GM and would be available in late 2007 or early 2008, according to Quinnell. In the future, "Adding the hybrid option would be an option to check off," as customers do today to request a turbo-charged engine, Quinnell said. The U.S. Environmental Protection Agency requires auto manufacturers to greatly reduce emissions for their 2007 model-year vehicles. Automakers are more likely to offer diesel hybrids in Europe before the United States gets them because diesel fuel is much more expensive there. Diesel vehicles have a much higher market penetration there, according to Benjamin, and integrating both hybrid and diesel technology could add up to $8,000 to the price of a vehicle. "Even (with gas at) $3 a gallon, $8,000 (more) is a lot to pay." GM's Freese agrees that meeting the emissions and budgetary requirements in the United States would be difficult. "North America is a challenge," he said. "The cost ends up being significant for some of the (emissions reducing) systems."