My 85-year-old mother is hard to impress as far as cars go, but she was mighty quick to heap praise on this one.

Within minutes of settling in the back seat she said: “This car is really quiet. I can hear your conversation in the front and I can never do that.”

While noiseless travel has been a hallmark of the Lexus brand since the first LS 400 whispered its way on to the roads almost 30 years ago, the engineering under the sleekly-styled bodywork has kept pace with the times.

So while the original LS used a whopping 4.0-litre V8, the latest NX 300h is a politically-correct hybrid with a powertrain designed for the 21st century.

Power comes from a smooth, efficient 2.5-litre petrol-electric, self-charging engine, developing over 150 horsepower. In addition, the car tested here was also fitted with all-wheel-drive, with a second 141 horsepower electric motor driving the rear wheels, so it is no slouch.

The combination delivers supremely relaxed and quiet motorway cruising, excellent ride comfort and responsive handling, with the realistic potential for squeezing 45mpg fuel consumption in day-to-day use.

Simply by flicking a dial on the centre console, you can choose between normal, eco and sport driving modes and a button next to the dial lets you engage an additional all-electric mode. In each mode, the accelerator action is adjusted according to whether economy or performance is prioritised and the system also simultaneously tweaks both the power steering assistance and suspension damping.

Since its launch four years ago, the NX has become a key model in the Lexus range accounting for roughly one in three Lexus sales across Europe, so the new model was clearly in no need of any radical change.

In has come a number of detailed changes to the external styling along with some new alloy wheel designs and colour options, but the main focus has been on the interior with a sportier and more luxurious feel to the cabin with larger multimedia displays and a revised air conditioning control panel.

Safety too has received a lift with a series of systems fitted as standard across the range, from a pre-collision system, adaptive cruise control and automatic high beam, to lane keeping assist with sway warning. Another system that continuously monitors road signs turns the road sign display red if you stray even 1mph over whatever limit is in place.

This information, along with the car’s speed, satellite navigation guidance, engine revs and audio settings, are all displayed on a 6.2-inch head-up display projected on the bottom part of the windscreen.

Another really useful piece of technology is the rear cross parking alert that uses radars to scan left and right behind you as you reverse out of a parking space and warns you of approaching traffic.

And, praise be, in the centre of the dashboard alongside all these gleaming colour multimedia displays, the 360-degree panoramic view monitor, touchpad controls and a 14-speaker Mark Levinson hi-fi, sits a beautiful, stylish analogue clock.

Despite its striking, sleek styling, the NX is properly practical with plenty of space inside, loads of rear knee-room and a high roofline giving lots of head clearance.

Luggage space too is generous and loading is improved with a power tailgate on the test car, along with a close-and-lock button next to the tailgate grab handle that automatically closes the tailgate and then locks the vehicle.

With upmarket looks, superb build quality and a refined ride, when it comes to travelling in luxury, mother knows best.

Auto facts

Model: Lexus NX 300h Premier

Price: £45,040 as tested

Insurance group: 33E (1-50)

Fuel consumption (combined): 54.3mpg

Top speed: 112mph

Length: 464cm/182.7in

Width: 184.5cm/72.6in

Luggage capacity: 16.7 cu ft

Fuel tank capacity: 12.3 gallons/56 litres

CO2 emissions: 121 g/km

Warranty: Three years/ 60,000 miles