Comprehensive emission characterisation of exhaust from alternative fuelled cars

Exhaust emissions from Euro 2-6a cars using diesel, gasoline, high concentration ethanol (E85) fuel and compressed natural gas (CNG) were studied comprehensively, with a focus on results obtained at −7 °C test temperature. Higher emissions than desired were noticed in some cases, e.g. elevated methane emissions from natural gas fuelled cars, as well as methane and acetaldehyde emissions from E85 fuelled flexible fuel vehicles. Additionally, mutagenicity of PM samples and oxidative potential of semivolatile samples were observed. However, emission performance improved significantly when moving from older to newer Euro 6a cars, showing that low tailpipe exhaust emissions can be achieved when combining new car technology with CNG, E85, gasoline and diesel fuels. Furthermore, the climate impact of these technologies could reduce by using renewable counterparts of these fuels. •Mutagenicity of PM and oxidative potential of semivolatiles were observed.•In some cases, elevated emissions of e.g. methane, aldehdydes, N2O, NH3, PN, semivolatiles.•Many tailpipe emissions were low for Euro 6a cars using CNG, E85, gasoline and diesel fuels.•Particularly low emissions for NGV/CNG, and PM emissions for FFV/E85.•Climate burden could be reduced by using renewable counterparts of fuels tested.