IT’S taken awhile, but Europe finally seems to have fallen for the whisper-quiet charms of Lexus. In the first six months of 2014 the marque notched up a record 25.4 per cent increase in European sales, making it the fastest growing premium brand across the continent.

Overall sales are still modest when measured against BMW, Mercedes and Audi but, long term, that could work in Lexus’s favour.

When a model is a permanent fixture in the UK best-seller charts (like the BMW 3-Series) can it really be considered any longer a ‘premium’ product? I’m not so sure, especially when scabby old Beemers start showing up in the ‘Cars for under £1,000’ small ads.

So what is driving the Lexus sales success?

The 3-Series baiting IS and the RX SUV are the biggest sellers but there are other top performers hidden in the figures. The GS hybrid line-up has accelerated strongly following the debut of the GS 300h at the end of 2013. Sales are up by an impressive 75 per cent - a vindication of the company’s policy of using petrol-electric drivelines to differentiate its cars from the German opposition.

ON THE ROAD: ​ The fourth generation GS is available in two versions: the GS 300h and the flagship GS450h. Although the 450h is an impressive machine, it’s the cheaper 300h that has galvanised sales.

The rear drive 300h combines a 141bhp electric motor with a 2.5-litre four-cylinder lean burn petrol engine. The engine’s good for 178bhp and the total powertrain output is 220bhp - more than enough for effortless acceleration and refined cruising.

The figures don’t tell the full story, though.

Lexus has unparallelled knowledge of hybrid drive systems and what makes them tick. The GS300h installation is mated to a computer-controlled continuously variable automatic transmission. Together they create a wonderfully smooth and quiet drivetrain perfectly in keeping with the Lexus concept of luxurious performance.

The 2.5-litre engine may only have four-cylinders (traditionally a car in this class would have six or eight cylinders for greater smoothness) but it feels as buttery smooth as a well-sucked Werther’s original. The instant power available from the electric motor imbues the GS300 with sufficient performance to please the enthusiast but also settles down to a barely perceptible hum when you’re loping along at 70mph on the motorway.

The GS was the first model to benefit from a company-wide drive to inject more passion into Lexus cars. The stiffer chassis has been redesigned for less unsprung mass, the suspension is fashioned from lightweight aluminium, the powertrain has user-selectable drive modes (Eco, Normal and Sport) and, if you want more of an edge, the F Sport and Premier models feature a variable suspension system which automatically adjusts all four wheels independently ‘on-the-fly’. The latter has a Sport Plus mode which prevents vehicle roll and reduces the steering gearing by ten per cent for improved response and feel.

ON THE INSIDE: ​ Although the latest GS has the same wheelbase as its predecessor, there’s more space on board. How? The rear seats have been redesigned with a steeper backrest angle and reshaped cushions. At the same time the front seatbacks are thinner (with no loss of comfort) which liberates 20mm more knee room and 25mm extra headroom.

The Lexus marque has always been about luxury and comfort and the GS is no different. High quality materials are used throughout the smart cabin. For instance, the instrument panel is fashioned from leather (with stitching colour matched with the interior), the audio system utilises milled aluminium knobs and the clock is forged from a single ingot of metal.

The Northern Echo:

​ WHAT DO YOU GET: ​ Lexus is all about the practical application of high technology - but sometimes even the most sophisticated computer comes a cropper.

The navigation system uses a new protocol (TFP - Traffic Flow Protection) which supposedly allows it to predict traffic jams and re-route around them. Sounds good, but on a fraught trip to London the sat nav decided the M25 would be like a car park in the late-afternoon and re-routed me ever deeper into central London. I realised what was happening but, being on my own, I was powerless to resist as the sat nav directed me into a rat run of choked roads, camera-monitored bus lanes and congestion charging zones (thank goodness for hybrid technology). It did the job but relaxing it wasn’t. I’d rather have sat motionless on the M25 for an hour tapping my foot to the superb audio system.

When I did get out of London, however, the sat nav successfully avoided a massive pile-up on the A1 and another crunch which closed the M1 that would have added even more frustration to my journey home.

In all, that London jaunt took more than eight hours - but afterwards I could at least attest to the comfort of the driver’s seat.

HOW PRACTICAL IS IT? ​ Hybrid powertrains often impact on a car’s practicality (all those batteries have to go somewhere, right?) but the GS is big enough to hide the extra kit without needing to stuff it all in the boot. As a result, the 300h has a 465 litre boot - a whopping 55 per cent larger than its predecessor.

The air conditioning system uses sensors which tell it if the front passenger seat is occupied. If it isn’t it automatically closes all the vents serving that seat. The same applies in the back.

The air con’s party tricks don’t stop there: it can layer the air mix so cool air combats the effects of sunshine through the windows, but the lower air mix warms your feet.

A deodorising filter blocks dust, pollen and exhaust fumes (handy when I was trapped in London traffic, at least I wasn’t choking on bus fumes). Negatively charged ions deodorise the seats and roof trim to keep the cabin clean.

The Northern Echo:

RUNNING COSTS: ​ As a full hybrid, the GS300h can be driven for short distances purely on its electric motor. The system can juggle the engine and the motor automatically but it’s also possible to switch to battery power manually. In town, the GS will spend more than 70 per cent of its time running in EV mode - good news for petrol consumption.

During the test I covered nearly 1,000 miles and average 43mpg - a terrific return for such a big, powerful saloon and, with exhaust emissions as low as 109g/km, you won’t pay a fortune for road tax either.

​ VERDICT: ​ Lexus has always been a towering tribute to Japanese build quality, peerless reliability and attention to detail. The G300h throws a dash of design flair and improved driving dynamics into the mix. It’s a worthy alternative to the Teutonic orthodoxy and fully deserving of its sales success.

​ Spec:​ Engine: ​4-cylinder in-line, 16-valve DOHC.

Power: ​178bhp@ 6,000 rpm (+ 141bhp - electric motor).

Torque: ​ 221 NM @ 4,200-5,400 rpm (+ 300NM - electric motor).

Top speed: ​119mph (46mph in EV mode).

0-62mph: ​9.2 seconds.

Fuel economy: ​43mpg on test.

CO2 emissions: ​109g/km.

Equipment: ​ Switchable driving modes, hall assist control, adaptive suspension, electronic parking brake, cruise, electric driver’s seat with memory function, leather upholstery, LED ambient lighting, dual zone climate, 12-speaker audio system with RDS and DAB tuner, 8-inch multimedia screen with remote touch interface, Lexus premium navigation system, Bluetooth, 12-volt accessory sockets, USB, aux input, daytime running lights, bi-xenon headlamps, rain-sensing wipers, alloy wheels.