I had this Sonic sedan as a rental after my 2011 Focus was rear-ended.
I'll begin with the good:
The seat of the Sonic was comfortable and the front cabin had a good amount of space. However, the armrests aren't even for the driver.
The Sonic is quick, responsive, and handles well. Toward the end, it was actually somewhat fun to drive.
The controls for the climate are your universal three-dial setup, which was a nice departure from my button-happy Focus. The heat was good. I didn't test the A/C.
I like the amber turn signals in the rear; all cars should have this.
That's about the only good I have to say about the car.
The A- and B-pillars are very thick, making vision difficult.
The belt line is very high and it feels like you're sitting in a bath tub.
The gauge cluster is cluttered, and I hate the blue-on-blue because it doesn't have good contrast. The dimmest setting was still too bright. I don't like how the tachometer was analog and everything else was digital. It looks goofy, and I had to take my eyes off the road to see my speed.
The radio was good, but the controls were confusing. I don't like the display; I'd rather have the time in the center of the screen, not the date. I wish the clock was a different color so it would stand out.
The trip computer was confusing to use. You have a menu button, a toggle switch, and a button to push. I'd rather have the system in my old Ford: three buttons; setup, info, and reset.
I wish they hadn't put those vertical storage cubbies on the dash. If they had put the vents where those cubbies are, they could have put covered storage in the cabin. Other than the two glove boxes, there is no covered storage area in the Sonic. I'm an ergonomist by trade, so I was sorely disappointed.
I can deal with all that, though, all of that, if it didn't get such terrible fuel mileage. I drove 220 miles and it took 10.6 gallons to do so; that's 20.8 MPG (60% city, 40% highway). I'm an easy driver, and I understand that this was a rental, but this is pathetic. I used to have a 2005 Taurus 3.0 V6 that got 22 MPG with 100% city driving. My Focus got 28 MPG with 60% city, 40% highway driving, so I didn't think 28 MPG out of the Sonic was unreasonable.
Other than the poor ergonomics and absolutely dismal fuel economy, this was a pretty decent car. But based on this rental, Chevy still has some work to do. I'd avoid the Sonic for the terrible gas mileage alone.