 The Volt requires premium gasoline with a minimum 91 or octane rating because the higher octane rating fuel permits the 10 @.@ 5 : 1 compression ratio engine to utilize more ignition timing advance in order to maximize its fuel efficiency by 5 to 10 % as compared to regular gasoline . For users who drive mostly in electric mode and to avoid maintenance problems caused by storing the same gasoline in the tank for months , the 2011 Volt has a sealed and pressurized fuel tank to avoid evaporation , and as a result , the fuel filler has to be depressurized before opening the tank . Also the engine management system monitors the time between engine running and it is programmed to prompt the driver to run past the 40 @-@ mile ( 64 km ) all @-@ electric range before recharging in order to consume some gasoline . If the driver does not run on gasoline , the system will automatically run the maintenance mode which starts the engine to consume some of the aging fuel and circulate the fluids within the engine . A configuration with an E85 flex @-@ fuel capable engine is under development and was expected to be available in 2013 . 
