My 2012 was always like this, even midgrade ran poorly. I just got used to always running premium so it would always preform as expected. Mine was like this brand new and after 95,000 miles when i traded it.
My 2015 sonic sure does run better on 87 octane, however the emissions recall did nothing for my 2012 cruze need for premium. Car ran smoother after the recall, but still ran poorly on regular 87 octane.Do you know if your car had the emissions recall done on it? That might help. The 2014 and later seems to be happier with the lower octane gas then the older models.