Rivals: BMW M3 vs. Mercedes-AMG C63 vs. Cadillac ATS-V

Can Cadillac's upstart ATS-V really challenge BMW's legendary M3 and Mercedes-AMG's thunderous C63 for sport-sedan supremacy?

Premium carmakers seem preoccupied these days with pushing out ever more mighty, more athletic SUVs. That's hardly surprising: High-riding, high-power leviathans like BMW's X6 M and Mercedes-AMG GLE63 also carry high profit margins. Luxury shoppers can't seem to get enough of them.

With their crow's nest seating positions and their steamroller-sized tires, super utes can be surprising fun, but for our money, it's the time-honored compact sport sedan that remains the industry's best combination of sport, luxury and everyday utility. So we've decided to kick off our new Roadshow Rivals series with a comparison of the Mercedes-AMG C63, Cadillac ATS-V and, of course, BMW's M3. The hope is to answer a simple question: which one best exemplifies the genre for today's buyer?

By "today's buyer," we mean the driver concerned about which model best blends street and track performance with everyday livability -- including a heaping helping of smart cabin and safety tech. For this kind of money (the cheapest model here starts at just over $60,000), these cars not only need to be jacks of all trades, they need to feel genuinely special, no matter the occasion.

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In order to get a well-rounded look, we collected all three for an autumnal blast on southeastern Michigan's meandering country roads, then spent a second day hot-lapping Michigan International Speedway's eight-turn, two-mile road course. We even staged an impromptu, highly unscientific drag race on the back straight, just for giggles. Naturally, we've also gone over these vehicles' styling, cabins and in-car tech with a fine-tooth comb.

Here are our findings. And before we go any further, let's just state for the record,

yes, we're as surprised as you are.

Third place: BMW M3

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BMW's M3 telegraphs its high-performance intent through its gaping air intakes and barrel-chested hood.

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We say "of course," regarding the BMW's inclusion in this test, because it's long been the segment's gold standard. Having a premium sport sedan comparison test without the M3 would be like December 31 without the ball drop, or a new celebrity baby without a ridiculous name. The term "icon" may be annoyingly overused these days, but this Munich Motorsports special has certainly earned it.

Such is the pace in the automotive world that the fifth-generation M3, introduced in 2014, is already the oldest car here. Known to aficionados and pedants by its internal F80 model designation, this latest M3 follows the industry trend of engine downsizing through the wonders of turbocharging. It's the first time an M3 has ever had forced-induction plumbing, and it's a shift that has rankled some of the faithful's most fervent nitpickers.

The new 3.0-liter, 425-horsepower, twin-turbo inline-six delivers sounds a bit like a FedEx truck upon cold startup and lacks the sonorous stylings of the Benz's bigger engine. It's safe to say the new car isn't nearly as stimulating as the banshee wail of the last M3's naturally aspirated V-8 en route to 8,250 revs. As it is, the engine's sound is attractive (and plenty loud), but you're never quite sure how much of the soundtrack is mechanical and how much is the electronic sound enhancer that pumps backing vocals through the stereo system.

The M3's I-6 makes up for any lack of auditory character by providing a wellspring of torque, with its 406-pound-feet-of-torque maximum available from just 1,850 revs, carrying on through to 5,500 rpm. This thing makes power everywhere, and it's hard to catch flat-footed, even when the dunce behind the wheel piles out of a hot corner with the slick six-speed manual in too high of a gear.

Even in unassuming virginal white, this BMW still looks properly aggressive thanks to its barrel-chested aluminum hood, scowling lower fascia and model-specific flared rear fenders (also aluminum) that shroud 19-inch alloys wrapped in sticky Michelin Pilot Super Sport rubber -- the same tire model as every car year. In terms of aggressiveness of appearance, the M3 splits the difference between the conservative Benz and the Cadillac's relentless angularity.

The M3 is the lightest of the three cars here, starting at 3,540 pounds, yet on both track and street, it doesn't feel quite as tossable or direct as the Cadillac. It does afford the best outward visibility of this trio, however, and that's important, but on our favorite sections of southeastern Michigan's spaghetti'd two-lane blacktop and on MIS' closed course, its steering was judged inferior to the others. And as Roadshow's Editor-In-Chief Tim Stevens noted, the M3's "Dynamic" traction control still reins things in a bit too much, which encourages understeer. "Set things up perfectly and it's fun, but the traction control just feels too limiting. And with the TC off, the car becomes a real handful."

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The M3's interior breaks little new ground, but is ergonomically sorted and all business.

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Getting the M3 "just so" takes a while, as it plainly has too many settings. Everything from suspension firmness to steering response to electronic safety net intervention points (stability control, traction control and so on) is adjustable. That's great for control freaks looking for an edge at the track, but it's less so in the real world, where road conditions constantly vary and simplicity is its own virtue.

Fortunately, there are a pair of driver-customizable M Drive buttons to save preferred presets, but the days of just getting in an unfamiliar sport sedan and piling down a B-road are gone. For the best results, you'll want to spend a few minutes tugging and pushing the iDrive controller this way and that to get the Bimmer's systems on the same page. Oddly, while the Cadillac offers a similar level of e-adjustability, it doesn't feel like it needs as much fiddling to get right.

Thankfully, you'll be in a comfy, supportive seat while adjusting those settings. And you'll be looking at a well-built interior that's all business. As Roadshow's Executive Producer Drew Stearne notes, "The chunky design of the controls in the BMW makes it feel like this car is harking back to a time when the M3 first started getting drivers excited. Its more minimalist approach is not unattractive, but it has little that leaps out and makes getting into the car more of an event." Beyond some lighted M3 crests in the seatbacks, the others seem to offer more options-list luxuries and whiz-bangery to personalize their cabins. At least iDrive is solid work once you familiarize yourself with it, plus there's a nifty optional integration feature for Wi-Fi-enabled GoPro cameras.

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The M escutcheons on the seatbacks glow at night.

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Pricing? Well, nobody said icons come cheaply. The M3 starts at $62,000 plus $950 for shipping, but ours spiraled all the way up to $81,425 delivered, including $1,000 for adaptive M suspension, $1,900 for lighthouse-spec LED cornering headlamps, $4,300 for the Executive package (heated wheel, park distance control sensors, smart key, rear view camera, satellite radio and head-up display) and a breathtaking $8,150 for carbon ceramic brakes. They're great for the track, but a bit too harsh for the street.

The M3 has been BMW's purest driver's car for ages, but that mantle now seems to have passed permanently to the smaller, cheaper M235i -- and shortly, the new M2. You can't get either in a four-door, of course, but with the money you save, you'll be able to buy an everyday sedan for those occasions when you need a back seat.

Second place: Mercedes-AMG C63

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The C63's badge-forward appearance says "luxe" more than "sport."

Marc Ganley/CNET

The last C63 AMG was one of our all-time favorite street cars. It gave up a scintilla or three of precision to the Bimmer on-track, but made up for it with its hilariously powerful 6.2-liter V-8, whose guttural bark was surely one of the best-sounding noises in the history of internal combustion. Even though its standard paddle-shift automatic could be occasionally dilatory in its responses, its drivetrain was great fun, especially when you were willing to oblige your inner hooligan in some sideways action.

The more things change, the more they stay the same. This new C63 has an entirely different chassis and engine, but its character has remained firmly intact. The model has dropped a family sedan's worth of engine displacement and is now down to a svelte 4.0 liters, but the reduction in capacity has been more than compensated for by a new biturbo breathing system. The forced-induction V-8 thus arrives with 469 horses and 479 pound-feet of torque, the latter slugging it out from just 1,750 revs. That's enough to hit 60 mph in a conservative-feeling 4 seconds flat and punch to a limited top speed of 155 mph, Mercedes promises.

Of course, those figures won't be good enough for some people, so the C63 S model we were provided with whips up 503 horses and 516 pound-feet. Unsurprisingly, the S ran away and hid from its rivals in our informal drag race time after time, and it also put daylight between itself and the others on anything resembling a straightaway. The S' extra power is great, but from where we sit, it isn't worth the extra $6,650 to drop a tenth from the 0-60 mph and have the top speed unbridled to 180 mph.

As it was, our C63 S AMG was optioned to over $91,000, a tally that included $2,690-worth of a shouldn't-this-be-standard Multimedia Package equipment (Comand infotainment system with navigation, voice control, rearview camera and so on); and $2,800 for advanced driver-assist systems including lane-keep assist, auto-brake with pedestrian detection and smart cruise control with steering assist. The biggest ding? $5,450 for front carbon ceramic brakes, a fitment we'd pass on. It's worth bearing in mind that the base C63 starts at $65,250 (plus $925 for shipping), so it's actually priced right on top of the BMW, provided you don't go crazy with options.

To step inside the C63 is to bear witness to where all those extra dollars went. Despite its jarring as-tested pricing, the Benz's cabin simply feels a class above in terms of materials and execution. The C63 had the "most attractive cabin to me by far," noted Stearne, a comment echoed by everyone present. Its vast expanse of open-pore wood, quality-feeling switchgear and excellent fit and finish clearly carried the day, and its snug bucket seats, flat-bottomed wheel and rubber-studded pedals proved both classy and sporty. Not everyone liked the freestanding mount of the tablet-like 8.4-inch central screen, but there were no gripes about the quality of the display itself, and Benz's latest-generation Comand infotainment system is quite good. Finally, the C63 has the largest back seat and the biggest trunk.

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The Benz's open-pore wood is gorgeous, as is its jewel-like switchgear.

Marc Ganley/CNET

On the track, the C63's prodigious power made for some tail-happy moments -- both deliberate and otherwise -- even with the traction control left on. Simply put, it could be a handful, but with steering precision and feedback somewhere between that of the Cadillac (best) and the BMW (worst), it was manageable, and even enjoyable. Stevens noted the C63 is a "total drift monster with the TC off, [yet it was] more controllable than the M3. Lurid power slides and smoke are the name of the game." With its best-in-class soundtrack underpinning the whole experience, the Benz proved unceasingly engaging.

That's really saying something, because not only is the C63 the heaviest car here at over 3,900 pounds, no manual transmission is available. Instead, we had to make friends with Benz's seven-cog AMG Speedshift transmission, which bins the traditional power-sapping torque converter of traditional automatics in favor of a small wet startup clutch. Thankfully, the unusual gearbox is actually very responsive when driven in anger. It's noticeably keener than the transmission in the last C63, particularly when the drive mode is set to Sport or Sport+, which brings along with it rev-matched downshifts and 100-millisecond upshifts. In exchange, however, it's not always a pleasant partner in daily traffic, especially when pulling away from stoplights under part throttle, where it can be slightly herky-jerky.

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With a jog wheel, finger-swipe pad and voice control, the C63 gives drivers real flexibility when it comes to inputs.

Marc Ganley/CNET

That blemish aside, the Benz's slightly less refined on-the-limit character actually plays well on the street, as driving always carries with it a real sense of occasion everywhere you go. The same can't be said for the C63's looks, as its appearance just doesn't feel as focused or athletic as the BMW or the Cadillac. Yes, it has an AMG-specific front fascia and a deck-lid spoiler, but in general, the C63 looks a little too buttoned up in this company.

And yet, even with what everyone was agreed was too conservative an appearance, most of our editors agreed that if cost was no object, they'd take home the Benz. Of course, even in this rarefied air, money does matter, and it goes some way toward explaining our surprising first-place finisher.

First place: Cadillac ATS-V

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The distinctive Cadillac ATS-V is a violent collision of hard angles, slashes and chevrons, yet it somehow all works.

Marc Ganley/Roadshow

Put down those pitchforks, German car fans. We're not simply handing the $70,000 ATS-V the championship belt because it's the cheapest car in this test. Not even because it's got the snarliest, most distinctive, and most "of the moment" appearance. The Cadillac is taking the win because it possesses the chassis that proved most at home when the pavement took a turn for the tight and interesting, whether on public roads or at MIS.

After decades of siring offspring with real weight problems, General Motors -- and in particular, Cadillac -- has finally learned the merits of both a proper diet and of splurging to keep weight in the right places. The ATS-V weighs 3,700 pounds -- not quite as light as the M3, but definitely less rotund than the 3,935-pound Benz. What's more, it possesses a near-perfect 51/49 front-to-rear weight balance.

Couple those realities with the tidiest overall dimensions here, and you're left with the chassis that's most eager to dive into corners and the one that feels most settled in quick transitional moments. That's in part because the ATS-V has the tightest wheelbase and in part because it has the best road feel through its steering wheel and optional Recaro seats ($2,300). This, and our tester didn't even have the optional downforce-producing aero kit.

The Caddy accomplishes all this without beating up the driver, too. Credit the ATS-V's magnetic ride control suspension, which feels both quicker to adjust and in possession of a wider bandwidth between touring comfort and sporty firmness, regardless of what mode the suspension is set in.

Despite not having any MSRP-bloating carbon ceramic rotors (and having the smallest discs here), the steel brakes on our test car performed beautifully and predictably, with superior feel.

The 3.6-liter twin-turbo V6's 464 horsepower and 445 pound-feet of torque is perfectly flexible, and the direct Tremec six-speed manual is matched by a nicely weighted clutch (an eight-speed automatic is optional) and aided by a flat-shift system, which lets you keep your right foot to the floor while banging the thing into the next gear. Cadillac says 0-to-60 hits in 3.8 seconds and a top speed of 189 mph, claims that feel believable.

Simply put, between its on-point suspension, slim dimensions, direct steering and willing powertrain, the Caddy is the easiest to hustle confidently down an unfamiliar road or piece of racetrack.

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The ATS-V's cramped cabin is further let down by its disappointing materials and lackluster CUE infotainment system.

Marc Ganley/CNET

That tidiness of footprint does the Caddy few favors inside, however, where it offers the most cramped cabin -- particularly in the back seat. Even in dimensions where the cabin isn't the tightest, it feels it, because high beltline and fast windshield rake combine to make it somewhat claustrophobic, especially in the funereal black of our test car. None of these cars offers particularly spacious rear quarters, but the Cadillac is definitely the runt of the litter.

In fact, it's the ATS-V's cockpit that's the biggest disappointment in the whole car -- it's simply not up to the aesthetic or hardware standards of the BMW, let alone those of the Benz. Its angular presentation feels like it's trying too hard and the plastics, as well as general fit and finish, are noticeably inferior. After our years of ranting, it should surprise absolutely no one that the Caddy's CUE system is the worst infotainment experience here by a country mile. Oh, it's quicker than it used to be, but it's still slow and doesn't look as good as the Germans'. Plus, the capacitive-touch switchgear below it for certain HVAC and audio functions is utterly dreadful. Stearne pronounced the entire cabin would be "a complete miss," if it weren't for its high feature count at such a low price.

Among other things, our tester included a head-up display, 4G LTE Wi-Fi hotspot, a hidden inductive phone charging, Recaro seats, the car's surprise-and-delight Performance Data Recorder System ($1,300), and a host of well-done optional active safety features. That's all for an as-delivered price of $70,405 -- over $10,000 cheaper than the Bimmer and over $20,000 less than the Merc. This, for a car that was better to drive, particularly on the track, where it offers five separate track modes for you to switch between to suit your grip levels. And your confidence.

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In the end, it's the Cadillac ATS-V that shakes its tail feathers at its German rivals.

Marc Ganley/CNET

Given that massive pricing gulf, we think it'd be smart for Cadillac to offer a premium interior package for a few grand that does away with those nasty gloss-black plastic surfaces and adds in more Alcantara. Some color choices beyond jet black would be welcome, too. Oh, and while GM is at it, a more bellowful exhaust option would really help. A car that looks this sinister deserves a more forceful soundtrack than it currently has. Beyond that, there's not a whole lot we'd change. The ATS-V is a a sparkling performer with genuine swagger at a fair-shake price.

As we noted at the top of our story, luxury automakers seem preoccupied with steroidal SUVs, but that doesn't mean they're leaving this class for dead. On the contrary, the compact premium sport sedan market is poised to heat up soon with hi-po versions of the Jaguar XE and Alfa Romeo Giulia. Audi may even even rejoin the party with a new RS4. And don't expect for BMW to take this defeat lying down -- it's just announced a new Competition Package with 444 horses.

Naturally, we'll be here to gather them all together and suffer through a few more days of on- and off-track testing.

We can hardly wait.