Premium gasoline in a Sonic LTZ http://blogs.insideline.com/roadtests/2012/09/2012-chevrolet-sonic-ltz-use-premium-in-the-heat.html "This will not come as a surprise to some of you -- nor did it to me. But there are those who insist on using the least expensive fuel they can find. That stategy will work in the Sonic, but you'll be driving a different car. Last week I posted about driving the Sonic in the heat and the various maladies this weather creates with its tiny turbo engine. After emptying the tank of 87 octane, I refilled with 91 and was immediately impressed with the difference. Not only was I less likely to stall when pulling away from a stop, but fewer downshifts were required for adequate accleration. The difference was more dramatic than I thought it would be. Weather remained a persistent 95 degrees. If I owned a Sonic with this engine I'd use 91. Always."