Luxury sedans review

When you're paying $60,000 or $70,000 for a luxury sedan, you expect to get a sumptuous interior, potent performance, a long list of features, extra comfort and convenience, and plenty of high-tech wizardry. But you also want a car that embraces your individual tastes and driving style.

Each of the three models we tested for this issue—the diesel-powered Mercedes-Benz E250 BlueTec and Audi A7, and the freshly redesigned Cadillac CTS—delivers in its own way. And each uses a distinctive formula to appeal to different buyers.

The new E250 is perhaps the most rational luxury car you'll find. It mixes a posh interior with an ultra-efficient turbodiesel engine, an 800-mile highway driving range, an impressive balance of ride and handling, and the type of practicality that makes it easy to live with. That combination earned it a stellar 98 score in our testing, which is second only to the Tesla Model S, at 99.

In contrast, the sleek  A7, with its sloping roof and coupelike body, puts the emphasis on style and pizzazz. What's hidden beneath that sleek silhouette, however, is a luxurious and functional cabin and a spirited turbodiesel V6 engine that—at 28 mpg overall—is almost as efficient as the E250's. Though the styling compromises rear visibility, the  A7's hatchback design provides a healthy measure of practicality. All of that helped the  A7 peg a solid score of 95, making it another of the highest-rated cars we've tested.

The Cadillac CTS is geared for the sports-sedan enthusiast. With its potent 321-hp V6 engine, excellent driving dynamics, and well-crafted interior, the CTS is legitimately fun to drive. But in our testing it lost points on practicality because of a relatively tight rear seat and trunk and the cumbersome, frustrating controls of its Cue infotainment system.

The CTS and the diesel versions of the E-Class and  A7 are too new for us to have reliability data, so we can't recommend them. The gas versions of the E-Class and A7 have had above average reliability.

The low-slung, sleekly raked  Audi A7, which is derived from the excellent  A6 sedan, is a coupelike four-door sedan that's similar in concept to the BMW 6 Series Gran Coupe and Mercedes-Benz CLS. That type of car usually places more emphasis on styling than on practicality. But with its generous interior proportions and the cargo-carrying versatility of its hatchback design, the  A7 actually does provide a healthy dose of usability. And unlike those competitors, the Audi seats five people instead of four, at least in a pinch.

We tested the  A7 TDI, which is powered by a new 240-hp turbodiesel  V6 that's possibly the nicest, perkiest, most unobtrusive diesel engine we've experienced. It's mated to an ultrasmooth eight-speed automatic transmission. The  A7 has plenty of grunt, and it also returned an impressive 28 mpg overall. A long cruising range—565 miles in mixed driving and about 800 on the highway—is another plus. Like other diesels, it needs the diesel exhaust fluid (DEF) refilled at every oil change.

In addition to its excellent fuel economy, the A7 delivers an impressive blend of luxury, sound driving dynamics, and an impeccably furnished cabin, all of which helped it earn a stellar road-test score of 95, ranking it among the best cars we've tested.

Power is abundant, with a hefty surge that's almost always ready to be tapped. Handling is responsive and secure but not as overtly sporty as, say, a Porsche Panamera. The ride is also very good, steady, and compliant, although the low-profile 20-inch tires, a $1,200 option, make the ride firmer than we'd like.

Interior finish, seat comfort, and driver accommodations are first class. But access isn't as good as in the  A6 because the doors are smaller and the roof line is lower. The rear seat is roomier than in most competitors, though it's not as hospitable as the  A6's.

Among the few shortcomings are the controls, which take some getting used to. There is an array of buttons to navigate, which force you to look down and away from the road to pick the right function, at least until you learn their location by feel. You can also perform many functions through steering-wheel-mounted buttons. Overall, however, they are more straightforward than the touch-sensitive capacitive controls used in Cadillac, Ford, and Lincoln models. There's also a touchpad that lets you select radio presets or even trace out letters with your finger to spell out addresses for the navigation system.

Though visibility is surprisingly good, the car's sleek styling hurts the rear view when parking or merging. The  A7 is generally very quiet, but a low-level diesel thrum that's audible at low speeds robs some refinement.

There's no getting around the fact that the  A7 experience doesn't come cheap. Even our  "base" Premium Plus model cost almost $71,000, with just a couple of modest options thrown in. The  A6 with the diesel engine starts at almost $10,000 less than the  A7.

Best version to get. The  A7's 3.0T supercharged  V6 engine is impressive, but the 3.0  TDI diesel delivers a better blend of performance and fuel economy. Even the "entry level" Premium Plus version comes well-equipped, with standard features such as heated front seats, a power tailgate, and a navigation system with voice control. We'd also add  Audi's side assist blind-spot monitoring system, which is part of a $600 option package or standard on the uplevel Prestige version. We expect that most  A7s will come with the optional 20-inch wheels, which look great but don't do any favors for the car's ride comfort or noise isolation.

Since its launch in 2003, the CTS sedan has been Cadillac's talented young star: a stylish, fun, and agile sports sedan and a fairly credible alternative to a BMW 5 Series or Mercedes-Benz E-Class. The redesigned 2014 model shed a couple of hundred pounds, grew 4 inches longer, and acquired a plusher, posher interior. In short, it emerged from GM's finishing school as the most driver-focused midsized luxury sedan you can buy.

The CTS delivers an inviting blend of comfort, quietness, and sporty driving performance. We bought the midtrim Luxury version, which comes with a 321-hp, 3.6-liter  V6. That should provide enough zip for most people, even though its 6.8-second 0-to-60-mph sprint time is actually a bit slower than the acceleration many competitors deliver.

If you want more zip, you can opt for the 420-hp twin-turbocharged  V6 in the high-end Vsport version, which dials up the fun meter to the max. The base  "Turbo" version of the CTS comes with a 272-hp, 2.0-liter turbo four-cylinder engine.

We chose all-wheel drive, which has increasingly become de rigueur for many luxury cars sold in the Snow Belt. That configuration brings a six-speed automatic transmission that shifts smoothly enough but isn't nearly as slick as the eight-speed that comes with rear-wheel-drive, six-cylinder CTSs. We measured 21 mpg overall with that combo, which is about par for the class.

In everyday cruising the CTS feels deft and light on its feet, and the steering is responsive and well-weighted. An aficionado might grouse that feedback isn't as authentic as in the last generation, but that's unlikely to bother most owners. At our track the body stayed level when we pushed it around fast turns, and the CTS kept its cool while threading our avoidance maneuver.

The ride is steady and composed, but it's also quite firm, so you feel some taut little jiggles on all but the most pristine pavement. While underway, cabin noise is very well suppressed. The stiff-walled 17-inch, run-flat tires conveyed very little road noise.

It's clear that Cadillac spared no expense in redecorating the interior, and the result is a world-class cabin with excellent fit and finish, acres of padding, and sumptuous genuine leather. The front seats are very comfortable, but the cabin is a little snug. The rear seat can accommodate two adults, though not very happily. The extra length that came with the redesign mostly wound up in the engine bay, allowing for a stylishly muscular front end but no extra leg room.

Despite its highlights, the CTS comes up frustratingly short in a couple of areas. Our biggest complaint centers on the controlsfor the Cue infotainment system, in particular the flush-mounted, touch-activated switches. You can't locate them by feel alone, and the controls often don't work as expected, so you need to take your eyes off the road to double-check them.

Climate and audio functions are controlled through a large touch screen, which has large fonts and is generally easy to read. But figuring out how to navigate the system is difficult, even for simple functions such as manual tuning. Using the audio-system voice or steering-wheel controls can help you avoid fussing with Cue. But overall the difficult-to-use system considerably hurt the car's score in our tests.

Another gripe is the CTS' small trunk, which is able to hold only two large suitcases and a couple of duffles. The 60/40-split rear seatbacks can be folded down to expand cargo space. For those who put a high priority on driving enjoyment, though, the CTS is hard to beat.

Best version to get. The Luxury trim provides the best blend of features for the price, including leather upholstery, heated front seats, and an impressive roster of up-to-date safety features, such as forward-collision, lane-departure, and blind-spot warning systems. If you don't need all-wheel drive, you can get the superior eight-speed automatic transmission by choosing a rear-wheel-drive version. Most cars will have the sunroof, $1,250, and navigation system, $905.

E-Class models have always performed well in our tests, thanks to their comfortable ride, responsive handling, and luxurious driving experience. And for 2014, the new E250 comes with a 2.1-liter turbodiesel four-cylinder engine that delivered an outstanding 30 mpg overall in our tests. Let's pause and take that in: We got the same fuel economy from a 4,345-pound, all-wheel-drive luxury sedan as we did from the small subcompact Honda Fit econocar. That's also 4 mpg better than the diesel-powered E350 we previously tested.

Moreover, the E250's impressive 41-mpg highway mileage and 21-gallon fuel tank make it a road-trip machine, providing a cruising range of more than 800 miles. You'll probably stop for a rest room break—or several—before you need to refill the tank.

With 195 hp and a whopping 369 pound-feet of torque, the E250 delivers impressive response and no sluggishness at startup, thanks in part to the smooth seven-speed automatic transmission. Even when running in  "Eco" mode, the E250 doesn't feel flat-footed.

One note: The diesel engine requires refills of diesel exhaust fluid (DEF) at every oil change. If you do it yourself, expect to pay about $40 for the fluid at an auto-parts store; having a dealer handle the job could cost several hundred dollars.

The E250's handling is quite agile, with quick, well-weighted steering and limited body lean when cornering. When pushed to its handling limits at our track, the car proved secure and achieved surprisingly high speeds in turns, with commendable balance, composure, and predictability.

Mercedes offers Luxury and Sport trims, each delivering a distinct ride quality. We'd opt for the Luxury version, an optimum balance between comfort and sportiness. The suspension mops up almost every bump no matter how rough the road. Sport-trim versions are markedly stiffer.

The E-Class puts comfort and functionality over flash. Upright styling brings big windows, and visibility is among the best of any sedan we've tested. But a backup camera is available only as part of a $3,870 option package. And if the in-dash display is turned off, you can't see the camera's image; that is annoying and potentially a safety concern.

Fit and finish is impeccable. The faux-leather MB-Tex upholstery on the seats is a stellar imitation. Every panel fits together precisely, and almost all surfaces are covered with soft-touch materials or are dressed in swaths of wood or chrome trim.

The firm, well-padded seats are extremely comfortable and supportive, and there's plenty of head, leg, and knee room. Two adults will be comfortable in the rear, but an adult in the center position will find little leg room.

Although the controls aren't simple, they're among the most straightforward we've seen in a luxury sedan. The easy-to-read 7-inch screen is coupled with a central control knob that handles many infotainment functions, including audio tuning. The climate and basic audio controls use dedicated knobs and buttons.

Most of our complaints center on the steering-wheel stalks. Bunched together on the left side of the column are stalks for the cruise control and the turn signal and wiper functions, as well as the tilt/telescopic adjustments for the steering wheel. On the right side is an awkward electronic transmission shift lever that takes some getting used to.

Pairing an iPhone is simple, but  Android devices take a bit more effort. Bluetooth streams well, and though there is a USB port, the iPhone connector cable is for the older type, preceding the iPhone 5. Voice commands work well enough but aren't as seamless as systems in some cars.

The DEF tank takes space normally used for the spare tire, so the E250 uses run-flat tires. Still, the trunk is roomy, and the trunk lid conveniently springs fully open every time.

In the end, it's no surprise that this excellent, fuel-efficient car scored a 98 in our road tests, second only to the Tesla Model S.

Best version to get. Both the diesel and the 3.5-liter gasoline-powered  V6 are excellent engines; choosing one may simply come down to which you value more: efficiency or performance. If you live where it snows, you'll probably want the $2,500  4Matic all-wheel drive. The wagon version is a practical alternative to an SUV, but you can't get it with the diesel. If we were optioning our test car from scratch, we'd get the $3,870 Premium I package (with navigation, heated seats, and a backup camera), the no-charge luxury package (17-inch wheels and comfort suspension), a $440 split-folding rear seat, and the $875 lane-tracking package (Blind Spot and Lane Keeping  Assist), for a total of $60,010.

Diesel engines, such as those in our Audi  A7 and Mercedes-Benz E250 BlueTec, are about 30 percent more efficient than a similar-sized gasoline engine. But how do they compare with an electric powertrain? To find out, we compared the performance of our  A7 to its electric-powered competitor, the Tesla Model S, which has similar proportions.

The Tesla has the edge in performance, using its 362-hp electric drive system to deliver a blistering 5.6-second 0-to-60-mph sprint. Though diesel engines aren't generally known for potent acceleration, the  A7's 240-hp turbodiesel  V6 holds up its end of the comparison, delivering a quick 6.6 time from 0 to 60 mph, only a second slower.

When it comes to efficiency, the Tesla is a runaway. The  A7 gets an impressive 28 mpg overall, but the Model S delivers the equivalent of 84 mpg. That translates into only 4.4 cents per mile for the Tesla (based on an electricity rate of  11 cents per kilowatt- hour) vs. 14.3 cents for the Audi (based on diesel costing $4.00 per gallon).

The trade-off is in convenience and practicality. With its 20-gallon fuel tank, the A7 can travel about 565 miles in mixed driving or 810 on the highway before refueling, which takes about 5 minutes at any of thousands of stations nationwide that pump diesel fuel. The Model S can go about 225 miles in good conditions before needing recharging. That's more than adequate for daily around- town driving but can be a handicap on a longer trip. A full charge takes about 5 hours using a special Tesla-provided charging station at your home. You can also use one of a Tesla's relatively few public Supercharger locations, which can fill the battery to half of its capacity in 30 minutes.

For most people, the less-expensive  A7 is the more practical choice, although the cheaper-to-run and whisper-quiet Tesla is an excellent choice for those who can live within its limitations.

As automakers try to pack more features into a car's limited dashboard space, control systems have become much more complex and often overly complicated. When shopping for a car, it's critical that you thoroughly check out those systems to see how easy it is to perform common functions, operate controls, read the screen, and navigate the system.

Each of the luxury cars in this issue takes a different approach to its control system, which highlights some of the things that manufacturers get right … and wrong.

Mercedes-Benz E250 BlueTec. This car uses the most conventional system. Climate and some audio functions are controlled through traditional buttons and knobs. Other functions are accessed through an in-dash display screen, which is navigated with a multifunction controller knob on the center console. The screen's layout is straightforward, connecting a phone is simple, and the center knob can also be used as a radio tuning knob or to scroll through presets. Each car has convenient steering-wheel-mounted controls to receive and end phone calls. Overall, the E250's system is the easiest of the three to use.

Audi A7. The  Audi also uses a display screen and controller knob, but rather than having the supplemental hard buttons mounted on the dash, they are arranged flat on the center console. That forces you to look down and away from the road to see them. Also, the knob is counterintuitive; turning it right goes down the radio frequencies rather than up.

A unique feature is a touchpad that lets you trace out letters with a finger to, say, enter an address into the navigation system. Surprisingly, you can do that by feel alone, but you still wind up glancing over to the screen to see whether the system got it right. The  Audi wins some points for a very well- designed trip computer interface, controlled through steering-wheel buttons. Those controls also serve as shortcuts to audio volume, preset scrolling, and phone contact scrolling, as well as taking or ending calls.

Cadillac CTS. We found Cadillac's Cue system to be the most cumbersome to use. Particularly frustrating are the touch-sensitive buttons that are mounted flush on the dash and are used to make climate and radio adjustments. You can't predict whether they will do what you expect them to do. You need to touch just the right point—not the shiny bar that looks like a button, but the label above it—for just the right length of time; if you're too quick, it won't work. Audio volume and fan speed adjustments are made by sliding your finger across a touch-sensor bar. As you'd expect, doing any of that while driving isn't easy.  And even when you get it set, if you accidentally brush over the buttons, you can inadvertently change something.

The Cue's touch-screen layout is fine, but key icons come into view only when you move your finger close to the screen. Because you can't always see where you want to touch the screen until you've reached over to it, that adds an extra step and another layer of complexity. (Fortunately, you can turn off that feature.) Other gripes: Using the trip computer is fussy. The graphics are vivid, but they can be dazzling and overwhelming. And having to reach over to the screen may not be ideal for people with limited mobility. Excellent voice commands help somewhat, but we'd rather have controls that work easily.