http://BuyPutnamGM.com 877-246-9092 The standard engine on 2015 Chevy Sonic LS and LT models is a 1.8-liter four-cylinder that produces 138 horsepower and 125 pound-feet of torque. A five-speed manual transmission with a hill-hold feature is standard, and a six-speed automatic is available as an option. EPA-estimated fuel economy is 30 mpg combined (26 city/35 highway) with the manual transmission and 28 mpg combined (25 city/35 highway) with the automatic.