Price and equipmentFor many shoppers in the mid-sized luxury segment, paying nearly $62,000 for a relatively unknown brand might not be the obvious choice, but the sheer levels of equipment in this middle of the range Infiniti will certainly help build a badly needed reputation.

With the exception of a heated steering-wheel, the Q50 Premium diesel gets all the toys of the flagship hybrid premium variant minus the performance-enhancing V6/hybrid powertrain, four-wheel drive and sports suspension.

Tech-toys can be found throughout the Q50 interior with two large touchscreens dominating the dash allowing consolidated controls of the 14-speaker Bose sound-system, digital radio with RDS, Infiniti InTouch navigation, downloadable applications and any devices that are connected via the two USB ports, Bluetooth or SSD card slot.

The driver's heated and cooled leather seat has 10-way electric adjustability (8-way for the pasenger), the steering column also gets two-way electric adjustment, while all spots benefit from six bottle/cup holders and ducted and filtered climate-control.

Keyless entry and start, automatic headlights and wipers, auto-dimming rear-view mirror also come as standard in the premium diesel, and a plethora of subtle cool illumination LEDs are dotted around the interior.

Another TFT screen is nestled between the main tachometer and speedometer gauges – this time just five-inches – and relays on-board information to the driver.

Due to the positioning of power hardware, hybrid versions of the Q50 don’t get the 40/60 folding rear seats of the diesel range – a practical feature worth considering.

Infiniti offers the Q50 in eight different colours, but in reality the choice is from seven different somewhat drab tones or a red.

Thankfully the exterior styling does partly make up for the uninspiring colour choices and the big-cat like headlights stand out from a head-turning front end with a grille not entirely unlike the Lexus spindle. Coincidence?Nicely proportioned 19-inch wheels wearing run-flat tyres complete the package.

InteriorErgonomically speaking any seat in the Q50 cabin was a pleasant place to spend time with good adjustment of the front seats, a well laid-out and uncluttered dashboard and excellent rear-seat comfort.

The second-row pew was roomy and delightfully comfortable with ample leg-room for even lofty passengers.

The spartan dash is partly as a result of the sheer expanse of touch screens, which dominate a majority of the central console area.

The lower screen has a glossy finish with a higher resolution while the top screen was matte and more conventional in its appearance, which we found a little confusing to begin with.

Selections made on the lower screen sometimes brought up results and further actions in the top screen, which showed good integration of the systems but lacked logic. We would have preferred a continuous style throughout or maybe just one screen being touch sensitive.

The system also took a long time to boot-up after the ignition was switched on, preventing users from being able to turn the radio off for example, and generally took a few seconds to think about commands.

After a few hours of familiarisation the extensive information and entertainment system became more user-friendly.

We particularly liked how the navigation alerted us of a major public event and arranged another route to avoid road closures.

Auto-dipping headlights are a nice convenience and safety touch but the version in the Infinity seemed reluctant to apply full-beam even when on remote and very dark country roads.

While the comfort and quality of the Infiniti cabin is comparable with some much more expensive brands, it doesn't quite hit the high-notes in styling.

Compared to Lexus' excellent IS range, the interior is more conservative.

Engine and transmissionWhen it comes to the oily bits, Infiniti has borrowed some technology from Mercedes-Benz, and under the bonnet you will find a 2.1-litre diesel engine – not 2.2-litre as its name would have you believe.

The four-cylinder does a decent job of pushing the Q50's 1729kg mass around with 125kW and a useful 400Nm of torque, but performance certainly couldn't be described as sporty, with 100km/h taking 8.5 seconds from standstill.

At idle a noticeable amount of vibration made its way in to the cabin accompanied by an almost van-like diesel sound-track, which disappointingly detracted from the Q50's overall quality and refinement in other areas.

However, we forgave its slightly unrefined operation purely on the grounds of the impressive fuel-efficiency.

Don't be fooled by the hybrid technology in the more expensive option because the diesel is the efficiency pick, and Infiniti claim a staggering 5.2 litres per 100km is possible.

We didn't quite manage that figure but, idle-stop technology and a super-slippery 0.27 drag coefficient enabled a still commendable consumption of just 6.8 litres per 100km.

We particularly liked the real-time idle-stop timer, which calculated the quantity of fuel saved during each journey – a rate of about 100ml of diesel for every 10 minutes of inactivity if you were wondering.

A seven-speed automatic transmission sends power to the rear wheels and functioned smoothly with good intuitive shift-points, but occasionally swapped cogs with an unusual and unwelcome violence.

Manual selection of gears is possible, but the steering column mounted shift-paddles don't rotate with the steering-wheel so we preferred to let the well programmed transmission look after itself.

Ride and handlingWith all other technological tricks aside, the Infiniti Q50 is most notable above all else for one particular design feature. While it does have a conventional steering column fitted, under normal circumstances it doesn't use it.

All steering controls are received by angle sensors near the steering-wheel and sent to the electric power steering rack electronically, and only under emergency fail-safe conditions do any mechanical links come in to play.

Say goodbye to rack rattle over corrugations.

Infiniti deserves credit and recognition for being the first to implement a steer-by-wire system in a production vehicle and generally speaking, the system is very impressive.

The minimisation of mechanical components between steering wheel and road wheels has resulted in a lightning-fast turn in and an infinitely variable ratio enables unmatched customisation possibilities.

This first system to hit the roads is accomplished, but in its infancy, it can't quite match the feel of the real thing and, while we liked the speed and precision of the steering, we wanted more feedback.

Flicking through the various Infiniti Drive Modes to 'Sport' changes the gear-shift points, alters the steering characteristics and raises the engine revs, which annoyingly kept the engine out of the useful low-down torque.

We preferred to leave the setting in normal and instead use the custom mode to speed up the steering ratio while leaving everything else standard.

Piloting the Q50 through twisty roads was a pleasure and the confidence inspiring grip combined with predictable manners allowed us to maintain a good pace, especially at night when the impressive active xenon headlights came in to their own.

The taut rear-drive chassis was lively and rewarding at speed with a particular ability to carve-up faster sweeping bends with ease.

Cruising out of town is where the Q50 really excels though and, thanks in part to active noise cancellation, at 110km/h the cabin was almost eerily serene, with minimal road-noise, negligible wind-noise and the previously rattly engine settled down to quiet low revs.

The highly adjustable seats gave good support on long journeys and remained comfortable without being excessively soft. We loved spending time on the open-road in the Q50d.

Safety and servicingAdding to the already impressive equipment levels are a considerable selection of active safety features, from lane departure monitoring and prevention, forward collision warning and braking, a speed limiter, blind-spot monitoring, active cruise control and parking sensors all-round, complemented by a 360-degree maneuvering camera.

There is no doubt that with all the systems active, the top-spec Q50 does keep a close eye on any potential hazards, but the various collision mitigation systems could be a little hyperactive, and regularly intervened unnecessarily.

The forward collision warning would sound when approaching tight corners, while the back-up collision intervention alarmingly applied the brakes when a continuation of the reversing course would not have resulted in a collision.

For a driver paying attention to their surroundings, the volley of warnings, interventions and even a throttle pedal that would occasionally fight back at the driver could become tiresome – patronising even.

Active cruise control maintained a constant distance from leading vehicles with three pre-programmed settings to choose from, but the system did allow the car to exceed its set cruising speed on downhill sections of road.

Rather than simply flashing a warning from the dash, we would have preferred active intervention as is the case with many of its other safety systems.

If all that electronic kit doesn't keep you out of trouble the Q50 has front to rear curtain airbags, front driver and passenger and side thorax airbags.

All the expected electronic stability programs also come as standard.

The Q50 also scored a good 35.76 out of 37 in ANCAP testing, giving it the top five-star safety rating.

All new Infiniti models have a four-year/100,000km warranty covering all parts and accessories.

VerdictInfiniti still has a way to go if it is to catch its closest rival Lexus, but simply putting a well-built, sharply priced luxury mid-sized sedan on the table is a good start.

The Q50 has all the standard equipment and build-quality to take a good fight to the Toyota-owned luxury car-maker, but it needs to build a reputation over the coming years and this accomplished model will only help that process.

As a sporty proposition the top-spec diesel can't match its hybrid stablemate or close competition from Lexus' IS range, but with a serious amount of standard equipment and unusual kerbside looks, the Q50 premium diesel is sharply priced.

When all the hyperactive safety systems settle down and the Infinity is left in the hands of an enthusiastic driver or on an open road, the Q50 2.2d S Premium is a real pleasure to live with and the only thing stopping it worrying some other more prominent brands is basic consumer perception.

A few more potential customers may also wander in to showrooms if the range was available in some brighter colours instead of the Q50 shades of grey.

RivalsLexus IS250 ($55,900 before on-road costs).

Mercedes-Benz C200 CDI sedan ($63,400 before on-road costs).

Audi A4 2.0 TDI sedan ($57,900 before on-road costs).

SpecsMAKE/MODEL: Infiniti Q50 2.2d S Premium
ENGINE: 2.1-litre turbo diesel
LAYOUT: front engine, rear drive
POWER: 125kW@ 3200 - 4200rpm
TORQUE: 400Nm@ 1600 - 2800rpm
TRANSMISSION: 7-speed automatic
0-100km/h: 8.5 seconds
TOP SPEED: 230km/h
FUEL: 5.2L/100km (6.8 tested)
EMISSIONS: 138g/km CO2
WEIGHT: 1729kg
SUSPENSION: Double wishbone(f)/independent multi-link(r)
STEERING: Direct Adaptive Steering (DAS) (steer-by-wire)
BRAKES: 320mm vented disc(f) 308mm vented disc(r)
PRICE: From $61,900 before on-roads