The issue is that the EPA numbers for the 2.5-liter put the ATS in the thick of the playing field, in there with the 23 city/33 hwy of the BMW 328i, the 21 city/31 hwy of the Mercedes-Benz C250 Sport Sedan and the 22 city/30 hwy of the front-wheel drive Audi A4. But the Cadillac's 202-horsepower and 190 pound-feet mean it is down on power to the other cars in its class – 38 hp shy of the BMW, 39 lb-ft down on the Mercedes-Benz, for instance – at the same time, it is less expensive than the BMW and Mercedes.
Motor Trend reports that General Motors predicts 22 city/32 hwy for the more powerful 2.0-liter turbo that puts out 270 hp and 260 lb-ft, the same as it did for the 2.5-liter, and that's what could make for the biggest question mark. The 2.0-liter would give the ATS a leg up on others in its class – it's not for nothing that the ATS site uses this motor for comparison – and the $1,805 premium over an ATS with the 2.5-liter pegs it exactly to the 328i's $35,795 base price. If the stronger engine does return the same EPA numbers, then until we have a better idea of standard equipment, lots of folks will wonder whether $1,900 is enough monetary space to make a case for a markedly less powerful car that won't save you any money on gas.