[ATX78703]

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The ATS's 2.0-liter is rated by GM at 272 horsepower at 5,500 rpm and 260 pound-feet of torque from 1,500-5,500 rpm — pretty strong numbers for a wee four-cylinder. They're facilitated by direct injection and a twin-scroll turbo that heaves out an eyebrow-raising 20 psi of boost pressure.

Though Cadillac says it's not required, we ran premium fuel in the ATS. 91 octane, that is. 91 octane is better described as "middling" rather than "premium" when 93 and 94 octane are plentiful elsewhere in this great land, but it's what we get in Southern California. At least we have the pleasure of paying more for crappier fuel. Anyway, here's what we measured at the wheels:





From low revs the ATS's turbo-4 delivers strong thrust, peaking at 252 lb-ft at 4,000 rpm, easily backing up its rated torque. Peak power of 239 hp at the wheels is right about what one would expect, given driveline loss. Unlike highly boosted four-bangers of yore, there's not an abrupt transition into boost with this engine. This is a civilized power delivery, smooth and fuss-free. The ATS is surprisingly quiet at full whack, too. There's not much personality in the way this engine sounds, but at least it's unobtrusive.

You'll notice that the claimed flat torque plateau from 1,500-5,500 rpm is curiously absent in our chassis dyno result. This is a normal characteristic common among turbo engines we test. In producing an engine's rated output, the manufacturer runs the engine on an engine dyno, which loads the engine differently than does a chassis dyno. Thus our usual chassis dyno pulls cannot replicate the tabletop torque curves shown by manufacturers, and torque never arrives quite as low in the rev range.
That wavy-gravy torque curve characteristic you see above was present on every run that we performed in the ATS, possibly a result of the usual ignition timing modulations to avoid knock.





So far, so good. But how does the ATS's engine stack up to that of its obvious rival, the 2012 BMW 328i? It, too, packs a direct-injected 2.0-liter turbocharged four-cylinder.

Well, it just so happens we dyno-tested one of those recently, too:





It turns out these two modern turbo 2.0L DI fours are quite similar. The BMW ekes out a smidge more peak torque and holds its power better at high revs, but the general character is essentially interchangeable among the two engines. Neither are particularly rev-happy things, but there's solid meat in both torque curves where it's suitable for everyday driving.

Here's the wrinkle. BMW rates its engine significantly lower: 240 hp and 255 lb-ft of torque. So while on paper the ATS's engine appears to one-up the BMW N20 by 32 horses, there's very little between the two engines in the real world. In this case at least, German horses are larger.

As expected, BMW continues to underrate these engines. Overall, the numbers are kind of a wash between the 2, but the n20 has a much nicer looking curve for torque and peak for hp.

Thoughts?