The 2012 ROUSH CleanTech Ford F-250 and F-350 pickup trucks feature a 6.2-liter V8 engine and two tank options: in-bed 49-gal., or under-bed 25-gal. Compared with gasoline, vehicles fueled by propane produce 17% to 24% less greenhouse gases, 20% less nitrogen oxide, and up to 60% less carbon monoxide. ROUSH CleanTech.