Fuel-Flexible, Fuel Processors (F3P), producing hydrogen to power fuel cells, provide several options for future near zero emission vehicles. Hydrogen Burner Technology, Inc. (HBT) has established an under-oxidized-burner (UOB™) technology, patented and proven in commercial use for industrial hydrogen generation applications. HBT is developing a subsystem in cooperation with the U.S. Department of Energy based on the UOB™ technology. This F3P subsystem can produce a hydrogen rich product gas using a variety of gaseous or liquid fuels as the feed-stock. The resulting hydrogen rich gas stream (reformate) may be directly useable by proton exchange membrane (PEM) fuel cells powering electric driven vehicles. Several gaseous and liquid fuel results will be examined and the general considerations for feedstock reforming will be discussed. Direct attention will be paid to system efficiency, startup times, and carbon monoxide polishing development. Initial tests of the F3P have established that the system efficiency and reformat constitution meet the performance goals, while size and weight are still below set targets. Fully integrated advanced design concepts are being developed, which offer improved efficiency and reduced mass and volume.