Emission studies on bio/synthetic gasoline show mixed results depending on the production pathway.

A study by Larsen et al. (2007) tested a gasoline blend containing 70% Fischer-Tropsch (FT) product. The emission tests were carried out with a VW Golf 1.6 FSI of model year 2003. Hydrocarbon (HC) and carbon monoxide (CO) emissions for FT containing gasoline were lower than for regular gasoline, but NO_x emission were at somewhat higher level. While its particulate matter (PM) mass emission was among the lowest, the emissions of particle-associated polycyclic aromatic hydrocarbons (PAH) were the highest. The authors note that these results may not represent all FT gasolines. FT products can go through different treatment processes, which affect fuel chemistry and properties.

Aakko-Saksa et al. (2011) studied hydrotreatment of oils and fats to produce hydrocarbons for gasoline, including the exhaust emissions related to this renewable gasoline component. Substantial changes in exhaust emissions were not observed when gasoline containing renewable hydrocarbon component was compared with fossil gasoline. Renewable hydrocarbon component combined with bio-oxygenates enabled high bio-energy content of gasoline without losing compatibility with conventional gasoline cars.