Small Engines, Big Technology: Three Takes on the Big Luxury Sedan

BUYER’S GUIDE

Large luxury cars used to be powered by throaty, grumbling eight-cylinder engines. Cadillac had its old Northstar V-8s, Mercedes-Benz a 4.3-liter, and Volvo a 4.4-liter V-8 in the mid-priced offerings. But downsizing is all the rage these days, and all three of those manufacturers’ new mid-priced offerings are powered by diminutive 2.0-liter four-cylinder engines. Our testing suggests that you might not miss those extra cylinders.

The segment stalwarts are the ones leading the downsizing charge. The 2017 Mercedes-Benz E300 Sport is the German automaker’s bread-and-butter mid-priced midsize sedan. Starting at around $50K and selling well-equipped for nearly 70 large, the E-Class targets the heart of the luxury sedan market with semi-autonomous driving technology, baby S-Class luxury, and a four-cylinder engine cranking out a respectable 241 hp.

Cadillac has historically been synonymous with big engines. It sold high-tech V-16 engines through the middle of the Great Depression and has been known for its high-power V-8s since the ’60s. Yet its stunning don’t-call-it-a-flagship 2017 Cadillac CT6 2.0T Luxury offers an engine with a quarter of the cylinders of its V-16 cars, a tried-and-true 2.0-liter turbocharged I-4 making a stout 265 hp.

You can always count on the Swedes to be just a little bit different. Although the 2017 Volvo S90 T6 AWD Inscription makes just as much of a visual impression as the Caddy and Merc, it differs ever so slightly under the hood. Yes, it too has a 2.0-liter four-banger, but the S90’s is twin-charged, featuring both a supercharger and a turbocharger. The end result is a potent little engine making 316 hp. That’s V-8 territory.

So are these small-engined thoroughbreds engaging to drive? Can they deliver flagship luxury?

Each sedan in this test brings a serious amount of technology to the segment. The Cadillac, Mercedes-Benz, and Volvo each offer their manufacturer’s latest in semi-autonomous driving technology, because there’s no greater luxury than doing as little work as possible.

Although each of these three vehicles takes a fundamentally different approach to luxury, all come nearly loaded and comparably equipped for our $70,000 cutoff price. Yeah, they’re different sizes, but consumers don’t buy size. They buy price. The winner of this high-priced four-cylinder shootout must be great to drive, luxurious, and offer impressive autonomous-driving credentials.

Third Place: Cadillac CT6 2.0T Luxury

Big on Engineering, Short on Execution

Put the Cadillac through one corner, and it becomes immediately clear where Cadillac invested its money on the new CT6 sedan: chassis engineering. The CT6’s bones are phenomenal. Extensive use of aluminum gets this big car’s curb weight down to just 3,893 pounds, only 2 pounds heavier than the next-size-down E300, the lightest car here.

Ostensibly intended to bridge the gap between midsize and flagship luxury cars such as the E-Class and S-Class, the CT6 was designed to offer up the luxury and space of an executive bruiser like the big Merc while offering the driving experience of a midsize offering.

To the latter end, it excels; the CT6 may not have been designed to be a sports car, but it gives a fair approximation at the test track. Its 2.0-liter turbo-four packing 265 hp and 295 lb-ft of torque seems on paper to be overmatched for the Cadillac’s long, low, and wide proportions, but it’s our favorite engine available in the CT6. Paired with an eight-speed automatic, the Cadillac is the second-quickest of the trio to hit 60 mph, doing so in 6.4 seconds. Its drag strip performance is equally impressive, with the Caddy rolling through the quarter mile in 14.7 seconds at 92.8 mph.

Not impressive, compared to its Nordic and Germanic competition, is the CT6’s 60–0 braking performance of 117 feet. Our tester’s standard all-season tires may be to blame for this and for the CT6’s third-place figure-eight performance, which surprised us given how composed the Cadillac felt from behind the wheel. The CT6 lapped the figure eight in 26.7 seconds at 0.66 g.

The Cadillac’s on-road manners are hit and miss. On the interstate, the CT6 is an exceptional cruiser. “There’s a bit of ‘good old days Cadillac’ in the way it goes down the highway,” associate editor Scott Evans said. The car is quiet and comfortable with an especially well-mannered ride—considering the CT6 2.0T isn’t available with Cadillac’s Magnetic Ride Control suspension system. The turbo engine is pretty solid, too; it’s responsive and quite capable of keeping the big Cadillac going at autobahn-esque speeds. “Smooth and torquey,” senior features editor Jonny Lieberman said. “It’s amazing to me that 2.0-liter engines have come so far. A generation ago this is what V-8s felt like.” The eight-speed transmission is mostly up to snuff, too, although it did regularly exhibit rough 1-2 shifts, especially at parking-lot speeds.

Where the Cadillac could use some improvement is in the little details such as steering feel, as its steering is lacking the feedback we’ve come to expect from Cadillac. The bigger problem is the “safety” cinching seat belt, which attempts to slice the driver in two like a cheese wire every time you turn a corner with any modicum of pace. “The constant hugs from the seat belt drive me insane,” technical director Frank Markus said. “I’m almost tempted to remove my seat belt.” Don’t do this.

Cadillac’s radar cruise control and lane keep assist systems are stopgap measures until the brand’s delayed semi-autonomous Super Cruise system arrives. Unfortunately, Cadillac has decided that CT6 2.0T buyers don’t need radar cruise control, with the system only available on V-6-equipped cars. The radar cruise control system on a CT6 3.0TT we tested worked as-advertised, but the stopgap’s stopgap on the CT6 2.0T—a simple forward collision alert radar—is inadequate in a car of this class. The CT6’s cruise control can actually use the front-facing collision radar to sense the distance the Cadillac is from the car in front of it, The CT6’s lane keep assist function is also lacking; it’s fine when the road is well-marked and its curves exceedingly gentle, but once it does cross a line, the system ping-pongs the car back and forth between lane markers.

Unfortunately for the Cadillac, things don’t get better inside. The cavernous cabin gives a good first impression but falls apart on closer examination. First, the good: The cabin is nicely designed, if a bit understated. The front seats are well-bolstered, and the executive-spec back seat package is spacious and comfortable so long as you’re not sitting in the middle seat. The seats themselves are also wrapped in thick baseball-glove-looking leather. Sadly, it all falls apart from there. The material choices in the CT6 are downright perplexing with a weird mix of leather, carbon fiber, chrome, and plastics. Most frustrating are the deep-grain plastics above the beltline and hard-grain plastics that lurk below it. The switchgear quality is maddening, too, ranging from a bespoke steering wheel to parts-bin buttons on the doors and center console.

And then there’s CUE, Cadillac’s infotainment system, which has somehow, impossibly, been made worse with the addition of a track pad. Although the finger-trace pad provides haptic feedback to the user, it’s constantly overshooting the user’s intended command. You’re much better off ignoring it and just using CUE’s touchscreen—provided it’s working, of course, as it froze multiple times before eventually crapping out, taking USB connectivity and charging with it.

Also inexcusable was the difference in quality between the rear-camera mirror and the backup camera. The rear-camera mirror, which displays an image from a second rear-facing camera, looked like a 4K video on a flat screen—although the focal length of the lens was disorienting for some. Worse still, the standard backup camera image was ridiculously grainy and crude. Seeing the two images displayed simultaneously is confounding. “This car is way too expensive for this nonsense,” Evans said.

Ultimately, the Cadillac’s refined cruising manners and roomy cabin just aren’t enough to overcome the technology and quality gap between it and the top two finishers. Senior features editor Jonny Lieberman sums up our disappointment well. “I thought Cadillac moved to New York specifically to avoid crap like this,” he said. “This is not good enough. Cadillac has to improve.”

Second Place: 2017 Mercedes-Benz E300 Sport

Tight Package Delivers on the Road

Mercedes-Benz practically invented the modern midsize luxury sedan with the E-Class. With the 2017 E300, it proves that it still knows what it takes to be successful in an increasingly competitive segment. Mercedes’ formula for the new E-Class was a pretty simple one: Shrink the S-Class design, and squeeze in the brand’s new Drive Pilot semi-autonomous driving. Same sausage, different lengths.

Despite being the least powerful car by 24 horsepower, the E300 hangs tough at the test track. Mercedes’ ubiquitous 2.0-liter turbocharged I-4 makes 241 hp and 273 lb-ft of torque and comes paired to a Mercedes-developed nine-speed automatic. The 0–60 run takes 6.5 seconds, and it needs 14.9 seconds to roll through the quarter mile at 92.4 mph. Equipped with the optional Sport package, which includes uprated front brakes and summer tires, our E300 tester was an unsurprising performer in braking and handling tests. The Mercedes did the 60–0 test in a comparison-best 106 feet and similarly lapped the figure eight in a best time of 25.8 seconds at 0.70 g.

Although stellar at the track, the E300 left a majority of our judges wanting a little more refinement on the road. The nine-speed auto is hit and miss, quite literally; sometimes it shifts quickly and with precision, other times it clunks between gears and takes a good two-Mississippi count before shifting. “This transmission seems to get discombobulated and gave me some very hard shifts; its logic wasn’t terribly great, either,” Markus said. The E300’s engine feels plenty powerful at lower speeds, but it feels as though it runs out of steam at highway speeds while passing, likely the result of poor choice in transmission ratios. Thanks to that Sport package our E-Class came with, the Merc was pretty fun to fling around corners. But the same package hurts its ride quality and cabin noise, as the E300 both rode worse and was louder inside than the Volvo or Cadillac.

With the addition of Drive Pilot, the new E300 is the most technologically advanced car to come out of Mercedes-Benz since the current S-Class. In fact, some Benz engineers say the E300 system is more advanced. Oversimplifying things, Drive Pilot promises Tesla levels of semi-autonomy, combining radar cruise control, self-steering via lane keep assist, and automatic lane change, among other technologies. The cruise-control system maintains speed well and will hook itself a few car lengths behind the car in front of it at highway speeds. Lane keep assist works most of the time on well-marked roads. However, for consumers to readily adopt semi-self-driving systems, said systems need to work all of the time, which Drive Pilot doesn’t. The cruise control’s radar sensor would regularly get dirty from light road grime, disabling the system. Lane keep assist frequently struggled in dealing with sun glare, and it had trouble tracking road markers as highway speeds crept higher.

Although Drive Pilot was a disappointment, the rest of the tech in the E300’s cabin worked as advertised. Sporting the latest generation of Mercedes’ COMAND infotainment system, the E-Class sports a large 12.3-inch infotainment screen on top of the center stack, with our car featuring an identical screen replacing the instrument cluster. COMAND itself has a bit of a learning curve, the driver’s left and right thumbs controlling actions on each respective screen via steering wheel–mounted touchpads, but it works once you get the hang of it.

The rest of the E300’s cabin is pretty inelegant compared to the other two cars. The materials, such as the leatherette seats and wood grain, are mostly convincing. But there was still more cost cutting than we’re used to seeing from Mercedes, the padded dash topper being one example. More elegant materials can be ordered on the E300, but not without exceeding our $70,000 cutoff. And although the front seats are comfortable, there’s no overlooking the tight back-seat package on the E-Class compared to the Volvo and Cadillac. As executive editor Mark Rechtin said, “Not great as a table for four.”

Although the Mercedes E300 makes a good case for itself behind the wheel, its tight back-seat package and inconsistent self-driving suite combined with its test-highest $70,025 sticker price relegate it to second place.

First Place: 2017 Volvo S90 T6 AWD Inscription

Like Goldilocks, we find the Volvo to be “just right”

The Volvo XC90 blew us away in last year’s SUV of the Year testing, so it should be no surprise that the S90 T6 AWD Inscription captures the same magic as the high-riding SUV. Riding on the same platform and sporting the same powertrains as the XC90, the S90 is a lighter, faster, and equally luxurious version of our 2016 SUV of the Year winner.

The goodness starts under the hood, where the Volvo should serve as the prime example for why luxury sedans don’t need six- or eight-cylinder engines. Powered by a 2.0-liter I-4 that’s both supercharged for low-end grunt and turbocharged for high-rpm power, the S90 makes 316 hp and 295 lb-ft of torque running to all four wheels via an eight-speed automatic. The powertrain is good for a 5.6-second run to 60 mph and a 14.1-second quarter mile time at 98.9 mph. The S90’s braking and handling performance splits the difference between the CT6 and E300, stopping from 60 mph in 107 feet and lapping the figure eight in 26.3 seconds at 0.68 g.

On the road, the S90 is a sweetheart. “Excellent power delivery from this twin-charged engine,” Evans said. “It’s not wanting for power.” The Volvo’s engine is smooth, powerful, and refined—everything a luxury buyer could ask for. The S90’s eight-speed automatic doesn’t enjoy being rushed in Dynamic mode, but it shifts smoothly in normal driving. The Volvo handles well but isn’t as sporty as the other two. Its suspension, which features a Corvette-like transverse leaf spring in back, irons out most bumps rather well and minimizes roll, but the optional 20-inch wheels transmit more harshness and noise into the cabin than we’d like.

Volvo’s Pilot Assist system is easily the best of the three entrants, although it’s still lagging behind Tesla’s Autopilot benchmark in its effectiveness. Lane keep assist keeps the S90 pegged in the center of the lane through gentle highway curves, and the radar cruise control behaves as if it were a human driver. The system, like the others here, is less reliable once off a well-marked highway, but it’s still an order of magnitude more predictable than the Caddy or Merc.

Where the S90 really separates itself from the other two is inside. The light and airy cabin is cleanly executed and beautifully designed. The ultimate expression of Scandinavian minimalism, the flagship-level interior focuses on the essentials: leather, wood, and metal. “Elegant, genuine materials everywhere you look and touch,” road test editor Chris Walton said. Volvo’s iPad-like Sensus infotainment system also deserves recognition for how many features it packs into an incredibly intuitive and responsive 9.0-inch touchscreen display. The cabin is roomy, too, with bad back-friendly front bucket seats and a spacious back seat, which strikes a nice balance between the cramped Mercedes and limolike Cadillac. “They grow tall people in Sweden, so the back seat easily passes the 6-footer-behind-6-footer test,” Rechtin said. “The back seat has tons of legroom and loads of headroom.”

The price further elevates the Volvo’s standing in this comparison, as this nearly loaded S90 undercuts the Mercedes and Cadillac by three to four grand.

For its few faults, the Volvo S90 is the Goldilocks of the three: It’s not the outright sportiest, nor is it the roomiest, but its properly luxurious, the best to drive, and the best at driving itself. The Volvo S90, quite simply, is 2.0-liter luxury done right.

Third Place: Cadillac CT6 2.0T Luxury

The big Caddy looks good on paper but can’t deliver on the details.

Second Place: Mercedes-Benz E300 Sport

The segment stalwart is fun to drive but held back by its cramped cabin.

First Place: Volvo S90 T6 AWD Inscription

The Volvo strikes the right balance between drivability, luxury, and tech.