Natural gas (both compressed and liquefied) has consistently maintained its market lead over competing alternative fuels and technologies for several years, and it will continue that trend into 2004, according to industry players and stakeholders who responded to the magazine AltFuels Advisor's annual "Looking Ahead" survey, released on January 4. But two competitors, biodiesel and hybrid drives, are closing the gap quickly — in nearly every vehicle segment.Hybrid technology is a strong threat to natural gas in the commuter and passenger car, and medium-duty truck/van segments, according to the survey results. The introduction of home refueling devices for natural gas vehicles may keep the fuel at the top of the market for the near future, but it is unknown how the market will divide further out. And unlike heavy-duty or diesel applications, smaller light- and medium-duty vehicles are not likely to pair natural gas with onboard electricity for hybrid drives because of the expense, space, and weight considerations for both fuel systems.In medium- to heavy-duty vehicle applications, biodiesel is expected to nearly catch up to natural gas, particularly in vehicle segments that are historically diesel-engine dominated. Heavy-duty trucks, transit buses and refuse haulers powered by CNG and LNG are expected to outnumber those burning any other alternative fuel, but biodiesel is predicted to run a tight second place, the survey concluded.