Mercedes-Benz and Audi have inserted new entry-level compact cars into their lineup the past several years, with the CLA and the A3, respectively. These two have very different packaging, style, and driving personalities, and they appeal to an entirely different kind of buyer.
Which are you? To get there, a good starting point might be to point out all the similarities, and then home in on the differences.
Both the Mercedes-Benz CLA-Class and Audi A3 slot in beneath vaunted vehicles that used to be the least expensive offerings from these German brands (the C-Class and A4, respectively).
(The A3, of course, comes in a convertible variant that the CLA-Class doesn't offer. And both come in high-performance flavors, S3 and CLA45 AMG, that are striking in their own right—but shoppers of these vehicles will have an entirely different set of priorities.)
Both the CLA and the A3 are built on front-wheel-drive architectures with turbocharged inline-4 engines, and they're similar in size—but they go about delivering space, style, and performance in very different ways. The A3 keeps to a silhouette like the larger A4—abbreviated in back, better detailed at its sides—while the Mercedes-Benz CLA looks more aspirational, with its low, swoopy roofline, and a cockpit with plenty of SLK roadster influences.
The CLA, which has received some minor cosmetic improvements for 2017 to bring its front-end appearance especially more in line with current Mercedes products, is about 7 inches longer than the A3—sized more like mainstream compacts like the Honda Civic and Ford Focus. Its wheelbase is several inches longer, too. Despite that advantage, the low roofline makes the Mercedes-Benz feel tighter inside the cabin, though the front seats in both cars have adequate room. The CLA is simply more coupe-like than the A3, which has a more usable back seat, for sure.
Even in the A3, those in back will need to negotiate with those in front; the Audi's sunroof limits head room in back, too. The CLA has a bigger trunk; at 13.1 cubic feet, it's 3 cubic feet larger than that of A3 quattro models.
Strong turbocharged, direct-injected inline-4 engines power both cars, and each makes loads of torque down low, with no recognizable turbo lag. In the A3, both front-drive and all-wheel-drive models get a 220-horsepower, 2.0-liter inline-4 (2.0T). Meanwhile, all CLA250 models, whether with front- or 4Matic all-wheel drive, get a 208-hp, 2.0-liter inline-4. With either of these models, they're so smooth and versatile, that the only way you might ever miss a V-6 is in their engine note.
Transmissions are surprisingly close in layout and design, as well. The CLA250 has 7-speed dual-clutch automated gearbox, while the A3 has a 6-speed dual-clutch. Performance between these two models is comparable, with the A3 2.0T perhaps a few tenths of a second quicker to 60 mph; but we'll give Audi the edge here, not only because its 6-speed dual-clutch gearbox is more predictable and reassuring but also because of this mode's somewhat better drivability overall.
The CLA definitely rides better, and there's less road noise in the cabin, although it's not quite the sharp handler that the A3 is. We'd also put the A3's steering and brakes as a step above; it's well-weighted (Audi Drive Select lets you choose from several boost levels)—less artificially heavy and numb than in the CLA250—and brakes in the A3 are reassuring and easy to modulate.
Infotainment is a common cool factor. Both the CLA and A3 have advanced connectivity and entertainment systems packed with features. We'd place Audi's MMI system ahead of the CLA interface. The Audi system tucks smoothly inside the dash when the vehicle is parked (in the CLA it's fixed), and MMI includes stunning Google Earth and Street View maps, fed by a high-speed 4G LTE embedded data connection that you can share with your passengers and their devices.
The Mercedes CLA includes more standard safety features, though; radar-based Collision Prevention Assist is included, as is the Attention Assist system that helps prevent drowsy driving. Active-safety options in the Audi include blind-spot monitors and adaptive cruise control.
Outside of MMI, the A3 doesn't have many features, trims, or special materials to get excited about. It feels like a (VW) small car that's been dressed up for the task of Audi duty; on the other hand, the CLA feels finely detailed, as if the company tried to give this car some of the cues, as well as the ambiance of M-B's larger cars—as well as a few of its own.
The A3 outpoints the CLA 7.3 to 6.6 here for a couple reasons. First, the Audi has crash data, and it's very good. Second, the Audi has better standard features. While we'd argue that the Benz may look like a better luxury car, the Audi is a better "car" car. We'd pick the Benz for a ride to the valet lot, but the A3 for most other circumstances.