In a world full of similarly priced compact luxury crossovers, one way to differentiate yourself is with what's under the hood. That's the approach Infiniti has taken with the all-new 2019 Infiniti QX50. What might otherwise be yet another $50,000 crossover becomes intriguing if only because of Infiniti's brand-new VC-Turbo engine, and the QX50 is the first vehicle in the carmaker's lineup to be powered by it.

As the name implies, the VC-Turbo uses different compression ratios based on driving conditions. The compression ratio describes the volume of an engine cylinder when the piston is at the top versus the bottom of its travel. The higher the compression ratio, the more thermally efficiently the engine can run. But the turbochargers that are all but omnipresent in today's two-liter engines don't play nicely with high compression ratios, because the combustion can become erratic and possibly result in engine knock (unwanted detonation of the fuel-air mix).

Infiniti's solution involves replacing the usual connecting rod between the piston head and crankshaft with a multilink arrangement. As Ars Automotive Editor Jonathan Gitlin explained:

The variable-compression ratio technology works as follows. Instead of just having a connecting rod between the crankshaft and piston head, there's now a multilink arrangement around the crankshaft, with the con-rod attached to one end. At the other end is an actuator arm that's connected to a harmonic drive. It's this harmonic drive that controls the distance that the piston travels within the cylinder by changing the angle of the multilink and, therefore, the top-dead-center position of the piston. This means that the engine actually varies in displacement; when the compression ratio is at its lowest, the engine measures 1.997L compared to just 1.970L when compression is highest. Peak power is 268hp (200kW) at 5,600rpm, and peak torque is 280ft-lbs (380Nm) at 4,400rpm. According to Infiniti, the front-wheel-drive QX50 should get 27mpg, a 35 percent improvement on the outgoing V6-engined vehicle.

The VC-Turbo can operate with a compression ratio as low as 8:1 for maximum performance or as high as 14:1 for maximum efficiency. The engine can even switch to the more efficient Atkinson cycle at high compression. The VC-Turbo is capable of 268hp (123kW) and 280lb-ft (380Nm) of torque. Oddly enough, the QX50 I drove was front-wheel drive, although all-wheel drive is available as an option. The crossover has a shift-by-wire continuous variable transmission, which means no mechanical transmission linkage (and slightly more interior room).

Pricing for the QX50 starts at $36,650 for the FWD Pure trim. The Luxe trim starts at $39,400 and adds a panoramic moonroof, blind-spot warning, and LED fog lamps. My review car, on the other hand, came with the Essential package, which starts at $43,350 and adds a complete parking-camera system, leather-appointed interior, parking sensors, remote start, and a couple of other niceties. If you want AWD on the QX50, it costs an extra $1,800.

Variable compression, variable driving styles

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

To get the most out of the VC-Turbo, the QX50 offers three very different driving modes. While sport, normal, and economy settings are standard for SUVs, Infiniti's implementation in the QX50 makes for wildly varying driving modes, which is a good thing. Pair Sport mode with Dynamic+ steering, and the result is a crossover that feels light, fast, and nimble. Infiniti claims that the VC-Turbo engine eliminates turbo lag; I wouldn't go that far, but it's only marginally perceptible in Sport mode.

Infiniti uses its Direct Adaptive Steering in the QX50, a steer-by-wire system that is designed with driver-assist tech in mind. You'll notice the steer-by-wire action in the Dynamic and Dynamic+ steering modes, which might not be everyone's cup of tea. I had a hard time getting accustomed to it because the steering initially seemed too smooth and disconnected from the road. Turning the wheel felt nearly frictionless, sort of like someone dropped a fidget spinner into the steering column. Paired with the increased responsiveness and higher shift points of Sport mode, however, the system came to feel more appropriate. Dynamic steering was at its best on winding country roads where, combined with the QX50's profile and weight distribution, it made me feel like I was behind the wheel of something smallish and sporty. That's not something I can say about all of the compact crossovers I test.

Normal mode offers no surprises, but going into Eco mode makes the QX50 feel like an altogether different car. There's extra resistance in the gas pedal, and the steering switches to the more-traditional rack-electric power steering setup that feels heavier and maybe a little ponderous—the car just chugs along until it gets to the speed you want it at. The QX50 truly offers a bipolar driving experience.

Fuel economy in the QX50 is better than other vehicles in its class, like the Audi Q5 and BMW X3. The EPA ratings are 27mpg overall: 24mpg in the city and 31mpg on the highway. In a week of the usual mix of driving, I saw just 25.2mpg. That said, I spent the majority of the time driving in Sport mode because it was more fun. Mileage should be better if you stick to comfort and economy, although you may not enjoy driving the QX50 as much.

The QX50 is also Infiniti's first crossover or SUV to be equipped with ProPILOT Assist, which is also available in the Nissan Leaf. Consumer Reports recently ranked it as the number-three automated driving system currently on the market, trailing GM's SuperCruise and Tesla Autopilot. It is definitely a big step up from the earlier system we tried in the Q60 coupe two years ago

ProPILOT Assist is capable of following the contours of the road to keep the driver centered in the lane, and the adaptive cruise control works well in heavy traffic and start-and-stop situations—it just needs a light tap on the accelerator to get going once it's completely stopped. And if you keep your hands off the steering wheel for more than 10 seconds or so, you'll get an angry buzz and a warning indicator in the heads-up display. Unfortunately, you'll need to pay extra for the driver-assist tech: $2,550 for the ProASSIST and ProACTIVE packages.

Speaking of HUDs, that of the QX50 isn't as well executed as the displays found in BMWs, Audis, and Volvos. Speed and driver-assist stuff is relegated to the right quarter of the heads-up display, and if you tend to slouch over to the right, some of it will be out of view while you drive. The left three-quarters of the HUD are used for warnings and navigation—stuff you don't need to see most of the time you are behind the wheel.

Interior life

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

BradleyWarren Photography

The QX50 is nicely appointed, at least with the Essential package. My review car had an "ultrasuede" headliner, leather-appointed eight-way power adjustable front seats with lumbar support for the driver, and a leather-wrapped (unfortunately not heated) steering wheel. The driving position is comfortable, although the undulations of the hood make it difficult to determine where, exactly, the front of the car begins. (The hood slopes up slightly from the windshield.) The heated and cooled front-row seats could use thigh support, as they felt a tad too shallow.

There's nothing unusual about the instrument panel or steering wheel. Audio controls are on the left side of the steering wheel, and driver-assist functions are on the right. And there's the usual small HD display between the tachometer and speedometer that can be configured to show things like tire pressure, the compression ratio of the VC-Turbo engine, and what radio station you're listening to.

Infiniti went with a tan, brown, and beige color palette for the interior, with some contrast stitching and maple trim accents in the dashboard.

My biggest complaint about the QX50 is the center console and infotainment system. Previous models of the QX50 (and the current QX60—which I will be reviewing) had a single display above the climate control and stereo system with a host of buttons dedicated to specific functions. Infiniti has moved away from that, embracing a two-screen setup. Unfortunately, the implementation leaves a lot to be desired. The top touchscreen display, with a matte finish, is used solely for maps, parking camera, and phone calls. The navigation system in the QX50 looks dated, and the map isn't up to date, which I noticed when looking for a freeway entrance that was opened in November 2016 that didn't show up on the map.

The bottom screen is glossy, and that's where you control the radio, access vehicle settings, and pair your smartphone. Underneath it are audio, menu, and climate buttons. It's a basic touch-screen, tile interface. While it looks crisp, the UI and design feel dated in late 2018, especially when compared to Volvo and Audi's infotainment systems. There are six climate control buttons and two for seat comfort (heating and cooling) on each side of the display, which I found annoying. Trying to adjust the fan speed or temperature required me to take my eyes off the road, and there's a steep muscle-memory learning curve involved in mastering it.

Topping it all off is a knob to the right of the shifter on the center console that controls the upper display, like camera selection and map zoom. The combined effect of two touch screens, a bunch of buttons, and a rotary knob is clunky, and the whole mess feels out of place in what is otherwise a very technology-forward vehicle.

The backseat

Backseat passengers will find heated seats, their own climate control settings, and a USB port. There's also a drop-down armrest, and the rear seats fold down in the predictable 60-40 pattern to increase the cargo volume from a very respectable 31.1 cubic feet (880L) to 64.4 cubic feet (1,824L), which is a fair bit more than other cars in the QX50's class.

Infiniti has a solid little crossover in the QX50. The drive-by-wire steering and transmission paired with the VC-Turbo engine and multiple driving modes make for an engaging vehicle that is fun to drive and handles nicely. You won't hear a lot of noise from outside the car or from the engine. There's a pleasant balance between sportiness and comfort that is sometimes missing in this segment, and the car itself is nice to look at with its curves and slopes. My biggest complaint comes from the infotainment system—which feels out of place in a car that's otherwise brimming with technical innovation—and the lack of support for CarPlay and Android Auto. But taken all together, Infiniti has come up with a worthy competitor to the likes of Audi, BMW, and Volvo with the QX50.