What is it?:

More fresh fodder for the heavy-of-wallet luxury SUV buyer, should the lustre already be wearing off the six-month-old Audi Q7, Volvo XC90 or Mercedes-Benz GLE on the driveway. We drove the new, fourth-generation Lexus RX in Europe, in left-hand-drive form, only last month. Now’s our chance to see how it copes with British roads, in otherwise identical, top-of-the-range Premier trim.

The all-new car is no softly-softly rehash. Built on a stiffened and extended all-steel platform, it is a sizeable 120mm longer than the outgoing RX, with half of that extra length added within the wheelbase in order to address one of the car’s long-standing shortcomings: a deficit of cabin space.

An aerodynamic body design is alleged to deliver telling improvements on cruising efficiency and refinement, while slightly softened suspension springs and stiffened bushings, steering mounts and anti-roll bars have been adopted in order to supersede the excitable ride of the outgoing RX, with the accepted dynamic compromise of the car becoming more of a luxury family cruiser. Over all of that, Lexus has wrapped a body styled more adventurously than that of its predecessor, to which fans of the brand’s alternative aesthetic should quickly warm.

There are only two powertrain options in the RX range: a 235bhp 2.0-litre turbocharged petrol, badged RX200t, and our 308bhp RX450h, which combines a 259bhp 3.5-litre V6 petrol engine with an electric motor mounted on each axle.

With CO2 emissions from 120g/km, the 450h offers a generous equipment level as well as the prospect of a £100-a-month company car tax saving to those who might otherwise buy a six-cylinder diesel alternative.

What’s it like?:

At once a significantly better high-class soft-roader – and probably a better Lexus – than ever the RX has been before, doing everything that Lexus’s established customer base will expect of it, and some things much better than the outgoing car did. And while it’s no more diverting as a driver’s car, and still not a particularly economical example of the big SUV breed, the RX’s new-found dynamic maturity suits it well.

Inside, readily apparent material quality and excellent fit and finish distinguish the cabin. As we’ve already written, the car’s fixtures and switches look and feel very substantial. High-end examples such as our test car even get polished, laser-etched wood trim on the centre console, made by the same people responsible for the panelling on Yamaha’s grand pianos. Annoyingly, there is no ‘piano black’ option (oh, the irony).

Passenger space is now more than adequate, although still a bit tight in both rows of seats on outright headroom for larger adults. Boot space isn’t generous enough to write home about but it’s fairly plentiful – and expandable via back seats that slide, tilt and fold.

On the move, the RX450h is outstandingly refined even under combustive power. The V6 petrol engine’s noise and vibration are well suppressed, and both wind and road noise are kept at an impressive low. The car’s ride is compliant, quiet and relaxed but can be tripped up over more severe intrusions, which the continuously variable dampers of our test car seemed to struggle to smooth out.

Body control is very respectable and steering response is decent, with good weight and pace in the wheel although little perceptible road feel. Grip levels were only moderately good on the 18in wheels of our test car, with understeer presenting in the car’s handling mix quite early on – but the car’s traction and stability controls keep a stern check on your line when inevitably called upon.

The car’s hybrid powertrain feels like a marginally cleverer, stronger take on what went before: more muscular on a part throttle and a bit faster and smoother in blending power sources. It is, however, still frustrating in manual mode, and likewise in general when you want to feel a close mechanical connection with the car. Typical daily driving produced 30-35mpg from it, according to the trip computer. Acceptable economy, but no selling point in itself.