Emissions with Reformulated Gasoline and Methanol Blends in 1992 and 1993 Model Year Vehicles 941969

Exhaust and hot soak evaporative emissions were measured in a fleet of 1993 production flexible/variable-fueled vehicles on methanol fuels blended with a reformulated gasoline. A fleet of 1993 California Tier 1 gasoline vehicles was also tested on the same reformulated gasoline blended to meet the specifications of California Phase 2 fuel. Ozone-forming reactivity, expressed as reactivity weighted emissions and specific reactivity, was calculated using 1991 SAPRC and 1994 CBM MIR and MOR factors. Within the FFV/VFV fleet, FTP exhaust and reactivity weighted emissions were significantly lower by 18 to 32% with Phase 2 gasoline relative to Industry Average gasoline. With the exception of greater NMOG emissions with the M85 blends, and lower OMHCE emissions with M85 blended with Industry Average gasoline, exhaust organic emissions, CO and NOx with the methanol fuels were not significantly different than their base gasolines. M85 reactivity weighted emissions were, however, significantly lower by 25 to 32% than Industry Average gasoline, but were not significantly different from Phase 2 gasoline using both photochemical mechanisms and reactivity scales. Exhaust specific reactivity was significantly lower by 50 to 55% for the M85 blends relative to gasoline, and by 6% to 8% for Phase 2 gasoline relative to Industry Average gasoline.

With respect to EPA designated toxic air pollutants, benzene and 1, 3-butadiene were significantly lower by 44 to 80% with Phase 2 gasoline relative to Industry Average and with the M85 blends relative to their base gasolines. Formaldehyde increased ten-fold with M85 fuels relative to base gasolines. Lower benzene and 1, 3-butadiene emissions drove aggregate toxics significantly lower by 40% with Phase 2 gasoline relative to Industry Average, while the increase in formaldehyde drove M85 aggregate toxics significantly greater by 57 to 146% relative to the gasolines.

Hot soak evaporative organic emissions were marginally lower with Phase 2 gasoline relative to Industry Average, but were greater with the M10 and M85 blends relative to gasoline. Hot soak benzene tracked fuel benzene levels and was also lower with Phase 2 gasoline and the M85 blends. Hot soak evaporative reactivity weighted emissions were not significantly different for any of the fuel comparisons, although hot soak specific reactivity was significantly lower by 26 to 49% with both photochemical mechanisms and reactivity scales for the methanol blends relative to gasoline.

Exhaust emissions and ozone-forming reactivity in the 1993 FFV/VFV fleet were nearly equivalent to the levels reported for the 1993 California Tier 1 gasoline fleet with Phase 2 gasoline.