This study examines infrastructure requirements and concerns associated with fuel safety, assuming that new fuels are introduced into the light-duty-vehicle (LDV) marketplace by the large-scale production of 3X vehicles-vehicles attaining three times the fuel economy of today's vehicles-under the Partnership for a New Generation of Vehicles (PNGV). The maximum-penetration scenario examined assumes that 3X vehicles enter the market in 2007 and capture a 60% share of the new LDV market by 2030. The case of all the 3X vehicles using a single new fuel and the case of a variety of new fuels being introduced are both of interest in defining potential concerns about infrastructure.