Although there are a few positives about the Cadillac ATS, there are some negatives that cannot be overlooked. The car comes with sleek exterior styling, precise handling, and a range of engines to suit your power needs. That might be where the positives stop, however, and the interior of the ATS is ranked as one of the worst of the luxury car class. Not only does the interior lack class, the infotainment system is difficult to use, and gas mileage is poor. In the city, you are looking at 16 miles to the gallon with some Cadillac ATS models.