Some hugely powerful cars have understated styling, some have rather restrained looks and then there is the Infiniti Q50 3.0t, which is so inconspicuous it could quietly vanish in any office car park.

While boy racers might enjoy the trappings of power with large spoilers, over-large air intakes and huge alloy wheels, there is something rather attractive about a car that keeps its potential under wraps.

On the Q50 there are precious few external clues to the awesome power lurking under the low-key bonnet, apart from a pair of chrome-trimmed exhaust tailpipes and the 3.0t badge on the side.

It is the 3.0t bit that is important, because of the five versions available of the car this one has an engine designed to take your breath away. This is a 3.0-litre, V6, twin-turbo petrol engine from Nissan pumping out 400 horsepower – five to six times that of a little family hatchback.

Slide inside and you are into a no-expense-spared cabin, with power-adjustable heated front leather-trimmed seats, dual-zone climate control, twin touchscreens, 14-speaker Bose sound system and lashings of aluminium trim.

All very smart and safe too, thanks to a battery of electronic systems from traction control to intelligent cruise control, all aimed at taming the remarkable power on tap.

Key to sharpening up the Japanese-built Q50 is the new ‘Direct Adaptive Steering’, which is designed to deliver more feel and feedback and give the car a shot at competing against the likes of the nimbler and more precise Audi A4 and BMW 3-Series.

All Q50 powertrains are matched to an advanced seven-speed, electronically-controlled automatic transmission with manual shift mode and steering column-mounted magnesium paddle shifters.

The new rear-wheel-drive Q50 also features Infiniti’s Dynamic Digital Suspension for the first time, which gives the sports saloon an excellent blend of ride comfort and agility. A choice of drive modes includes a personal setting so you can pick and mix between engine, suspension and steering characteristics.

Select the Sport+ setting and a more aggressive shift pattern with automatic up- and down-shifting at higher rpm kicks in. The dials glow red and it is all too easy to light up the rear tyres as they scrabble for grip.

More impressive in its way is the Eco setting that allowed me to actually exceed the manufacturer’s claimed combined fuel consumption figure on a 200-mile round trip to the coast with the on-board computer registering 32.5mpg.

Despite the car’s clear positioning as an out-and-out sports saloon, it is also surprisingly practical, thanks to a decent boot space and split/folding rear seats.

Infiniti is a serious player in the premier league in the United States but is much less well known here. So if you like to keep your car’s potency a well-guarded secret, the Q50 might be perfect.

Auto facts

Model: Infiniti Q50 3.0 Sport Tech

Price: £45,970

Insurance group: 34E (1-50)

Fuel consumption (combined): 31mpg

Top speed: 155mph

Length: 479cm/189in

Width: 182cm/71.6in

Luggage capacity: 17.6 cu ft.

Fuel tank capacity: 17.6 gallons/80 litres

CO2 emissions: 206 g/km

Warranty: Three years/60,000 miles