Two different engines are offered in the Sonic—a naturally aspirated, 1.8-liter four-cylinder base engine, and an available turbocharged 1.4-liter four that promises both improved performance and better gas mileage. Both are hand-me-downs from the Chevrolet Cruze, which means that in either case the Sonic has a friskier, more eager-and-responsive feel than you'll find in some other basic, affordable cars. A five-speed manual is standard with the 1.8-liter, while 1.4T versions get a standard six-speed; but in either case, the optional six-speed automatic transmission will be a popular choice.
While the power ratings aren't that much different between the two engines, there's a substantial difference in real-world performance. There's also a pretty big difference in refinement between these two engines. While both engines are rated at 138 horsepower, the 1.4T makes 23 pound-feet more torque—and it makes 90 percent of its peak torque all the way from 2,400 to 6,500 rpm, so you often don't truly need to downshift. It's also a very smooth, refined engine and feels a class above.
Actually, with the 1.4T, as we found with the larger Chevy Cruze, extra revs above 5,000 or so aren't really rewarded, and the throttle response can be a little too muted. On the other hand, to extract the 1.8-liter's full potential you'll need to rev it up past 4,000 rpm—where it can get noticeably louder and somewhat boomy.
The six-speed manual is actually very nice, with relatively short throws and direct, precise shift action, plus very smooth clutch takeup. So is the new six-speed automatic, which we found responsive and quick to downshift while just leaving it in Drive. You can control downshifts with a small plus/minus toggle button at the side of the shift lever. With either choice, though, consider that you'll be shifting more with the 1.8-liter engine.
There's a surprisingly capable chassis underneath the new Sonic; while this isn't the type of vehicle that driving enthusiasts would pick, it's nice to know that it does feel controllable, and actually fun to drive, on a curvy road—far more so than most econocars. The only blemish from an enthusiast's standpoint is that the Sonic's steering is more isolated than the steering in the Ford Fiesta, making it less sporty in feel yet less susceptible to vibration and road harshness—no doubt a tradeoff that 95 percent or more of buyers in this segment will be happy with. The one other perhaps more serious offense was that while brake performance was just fine, the pedal feel tended to be mushy.