Abstract: Octane number plays an important role in enabling optimal operation of gasoline engines. Vehicle
chassis dynamometer tests were conducted to investigate the impact of octane number on fuel economy and
the emissions of modern gasoline vehicles. The experiment conditions followed to the New European Drive
Cycle (NEDC). Five vehicles chose were equipped with Gasoline Direct Injection (GDI) or Port Fuel Injection (PFI),
using turbocharging technology or naturally aspirated technology. Six kinds of gasoline were fueled with the
RON (Research Octane Number) from 91.9 to 98.4. The results show that vehicles improve the fuel economy
of 1% with each 1.0 of RON increasing. Vehicles calibrated with higher octane (RON 97) achieve 2 times of
energy saving compared to vehicles with lower octane (RON 93). Using higher octane fuels makes vehicles with
advanced technologies achieve significant energy savings.

Key words: gasoline passenger cars, research octane number (RON), vehicle experiment, fuel efficiency, emissions