Manufacturers of mid-range executive cars tend to opt for turbodiesel power these days, at least when it comes to the European/UK markets writes Peter Carroll.

But Toyota’s luxury arm, Lexus, takes a different approach. Its £40,000 GS450h saloon is a hybrid and comes instead with a V6 petrol engine along with a battery-powered 650V electric motor.

The two combine to push out a total of 341hp – enough to match the performance of a V8.

Yet CO2 emissions are as low as 179g/km, while combined cycle fuel consumption is over 35mpg.

The hybrid power system certainly makes for an interesting driving experience. Press the Power button on the dash, put the car into gear and the near two-tonne GS450h glides away noiselessly.

As your speed increases, the petrol engine seamlessly takes over, and it’s hard to distinguish the crossover point.

Even when fully under petrol power, the Lexus remains impressively smooth and refined.

And it’s hugely powerful too. The GS may not ‘sound’ particularly sporty but it can hit 60mph in under six seconds,  making overtaking is a breeze.

Refinement levels are so high that drivers may find themselves needing to make a conscious effort to turn the engine off when they stop.

During my time with the test car, I pulled in at my local shop for a pint of milk and locked up the GS. It was only when I returned a couple of minutes later that I realised the engine was still running in its usual quiet and unobtrusive manner.

While the GS450h is undeniably quick, it’s not the sharpest drive in the executive class.

Its steering is light and not especially communicative, and the car feels slightly floaty with the suspension in its regular setting.

The Sport button tightens everything up – at the expense of some ride quality.

The GS has been given a minor refresh for 2010, both inside and out and now boasts a new front grille and a redesigned back end with larger rear lights.

There’s a revised Pre-Crash Safety system, along with an improved hard disk based satellite navigation system and DAB audio system. A reversing camera is standard.

The exterior styling is not especially dramatic, but the car’s lines are clean and tidy – Lexus designs are far more streamlined than when the brand launched two decades ago.

I’m not so sure about the interior, however. The dashboard lacks wow factor, especially considering the price of the car.

The wood veneer on the test car might go down well in the US but looks dated on this side of the Atlantic – and some of the switchgear appears to have been sourced from Toyota’s parts bin.

There are one or two operational ‘quirks’ too. A supposedly simple task like altering the wing mirrors requires a  secondary instrument cluster to be dropped down from the dashboard.

Internal space is good, however, and there’s room for three adults in the back. Not so the boot, which is compromised by location of the hybrid battery pack above the rear axle.

There are just 280 litres on offer – less than that in the new Fiesta.

Drivers may struggle to reach the claimed combined cycle economy rate of 37mpg unless they are exceptionally lightfooted.

I’d suggest 25-30mpg as a more realistic target. This is good for a petrol car but worse than the figures being achieved by the latest ultra-efficient diesels from the likes of BMW.

The GS450h, like many Lexus models, is probably at its best as a long distance cruiser: it’s got plenty of mod cons and the Levinson audio system sounds fantastic.

Despite the brand’s recent recall ‘issues’ Lexus generally has an excellent reputation for reliability and continues to perform outstandingly well in customer satisfaction surveys.

The battery pack, for example, is guaranteed for eight years, so should not be a source of anxiety for owners.

Those in search of a smooth, well-equipped car with a decent turn of pace when needed should check out the Lexus – and it may be even more tempting for executives who regularly need to visit London as it incurs no congestion charge.