Two flexible fuel vehicles (FFVs) using dielectric alcohol sensors have been designed and developed for mass production. One FFV will operate on gasoline or methanol up to 85% (M85). The second FFV will operate on gasoline or ethanol up to 85% (E85). Significant modification of a conventional dedicated gasoline engine was necessary in order to avoid major problems in the areas of preignition, engine wear and material compatibility.Operation on alcohol fuels provides for improved torque and horsepower over gasoline. Feedgas emission levels with alcohol fuels are lower than those with gasoline. However, this advantage is diminished at the tailpipe due to the long catalytic converter light-off times that result from the lower combustion temperatures which characterize alcohol fuels. Meeting evaporative emission regulations provided a challenge due to the high levels of vapor generated by low alcohol percentage fuel blends. Cold starting and hot starting characteristics are presented, which are also more difficult with the FFVs, as compared with dedicated gasoline vehicles.