I found this in my owners manual...
FUEL REQUIREMENTS — 1.4L/1.4L Turbo Engine
This engine is designed to meet all emission regulations, provide satisfactory fuel economy and performance when using high-quality unleaded “Regular” gasoline having a posted octane number of 87 as specified by the (R+M)/2 method. For optimum performance and fuel economy the use of “Premium” 91 octane gasoline or higher is recommended.
While operating on gasoline with an octane number of 87, hearing a light knocking sound from the engine is not a cause for concern. However, if the engine is heard making a heavy knocking sound, see your dealer immediately. Use of gasoline with an octane number lower than 87 can cause engine failure and may void or not be covered by the New Vehicle Limited Warranty.
Poor quality gasoline can cause problems such as hard starting, stalling, and hesitations. If you experience these symptoms, try another brand of gasoline before considering service for the vehicle.