Since I just learned that the 2.5L engine will not be used in 2017, I will change my review to the following:
Honestly, I bought this car because it is a four door with "rear wheel drive" and handling is good. The price was greatly discounted on the ATS base model so I decided to purchase it rather than a Chevy Malibu. If the Chevy Malibu was rear wheel drive, I would have purchased one of those. The other reason for buying the ATS, is that my wife did not want a larger car than this. I preferred to buy a Dodge Charger or Chrysler 300, but what can you do. Happy wife, happy life.
This car in my opinion is a driver's car. The 3.6 liter V6 is very responsive, it makes nice noises. The chassis corners flat, the transmission bangs shifts off with authority, the steering is great and with the V Sport brake option I can keep out of trouble.. When you want to be sedate and laid back the ATS accommodates so nicely. Drove the car out west for vacation. Interstate highways were gobbled up with 32 mpg. Twisty mountain roads are where this little sedan shines baby! In sport mode I was hitting apexes at twice the limit and asking for more.
When I got the got a few months ago, I was more excited about the electronics than the feel of the car. A few weeks into driving I discovered how erratic the transmission shifting was--you can actually feel the car going into gear and ,in some instances, the engine downshifts, which I consider unsafe. Even with disabling the "stop engine" mode, you can feel the noticeable changes in shifting. It is an unsatisfactory ride and I have owned or leased over 40 GM cars.