Lexus RX

This RX 450h+ model puts out 304bhp, makes 62mph in 6.5s and offers up to 43 miles of EAER-rated battery-only range.

In this Plug-in RX, the drive system works just as it does in plug-in versions of the Lexus NX and the Toyota RAV4, which also use the same dual-motor 'E-FOUR' AWD system and eCVT auto gearbox set-up.

Pressing a button near the gearstick lets you flip between 'EV' full-electric drive and the alternative 'HV' mode, the latter being more realistic for normal driving as it runs the car as a regular full-Hybrid, the software seamlessly blending in either petrol or electric power sources as required.

A full press on the same button connects you to a further 'Charge mode', which sees the engine note rise as it (rather inefficiently) charges the battery when you're driving.

All that might sound quite complicated, but driving an RX 450h+ really isn't.

You don't have to make driving mode choices unless you really want to because an additional 'Auto EV/HV' mode button is also provided, which essentially makes all the decisions for you.

Its choices seem effective too because that advertised 43 mile electric driving range figure turns out to be not beyond the bounds of achievability.

Unless of course you make full use of the performance: rest to 62mph takes 6.5s on the way to a maximum speed of 124mph. You'd expect a cossetting big Lexus SUV to ride serenely - particularly this one which, as we referenced earlier, has had quite a lot of work done on its damping.

All models get new multi-link rear suspension and the re-engineered all-round set-up's supposed to better absorb shock and vibration over uneven surfaces.

That might be, but to be frank, we were a bit disappointed with the end result, finding the car too easily troubled by transverse ridges and tarmac tears on secondary roads.

Yes even when fitted with the 'AVS' 'Adaptive Variable Suspension' system you can have with the top two trim levels, a set-up also supposed to have been heavily revised and fitted out with an extra 'Comfort' drive mode setting.

Around town, the RX rides more in keeping with its plush remit - and of course it manages beautifully at highway speeds. What else? Well the re-engineered electronically controlled braking system now delivers significantly more pedal feel.

You get shift paddles behind the steering wheel which deliver engine braking force in six steps.

And highway cruising speeds are as refined as you'd hope from a Hybrid, helped in the 450h+ plug-in model by the fact that there's less noise from the Hybrid engine as it can run at lower revs compared to this self-charging 350h variant.

Noise and vibration are also suppressed by plenty of insulation in the wing linings and front pillars - and the use of acoustic glass for the windscreen and front side windows.

The result is exemplary refinement that's difficult to better in this class.

Apart from the badging and the addition of a charging flap, there are no visual changes to set this RX 450h+ plug-in model apart from its self-charging Hybrid range counterparts.

The RX has gained a new visual lease of life in this fifth generation form, with a more dynamic look clearly influenced by the brand's full-electric RZ model and the smaller NX.

This car's so-called 'Next Chapter' design language delivers a more confident stance and emulates the 'spindle body' profile of the RZ.

The stylists were going for a more coupe-like feel, dropping the roofline by 10mm, plus there are big 21-inch wheels on most models. At the front, the spindle-shaped theme of the previous model is retained, though not as obviously because it's been applied to the entire front end, not just the grille.

The top part of the grille spindle is now blocked off (presumably in a nod to the EV revolution) and the rest of it merges into the body along its edges.

Slim LED headlamp units with their tick-shaped daytime running light strips are familiar.

There's just the standard five-seat body shape available.

Under the skin sits the same GA-K platform used in the smaller NX 450h+ model, so it's had to be significantly stretched here. Inside up-front, there's a driver-focused minimalist dash, with the usual digital instrument cluster and enveloping multi-power-adjustable seats trimmed in various grades of leather.

Infotainment's taken care of by a standard 14.0-inch central infotainment touchscreen incorporating "Hey Lexus" voice control system, 'Apple CarPlay'/'Android Auto' smartphone-mirroring and cloud-based navigation.

Plus most models get a customisable ambient lighting system with 64 colours and 14 pre-set themes. In the rear, this fifth generation RX design's 60mm wheelbase increase frees up useful extra leg space.

The seat base doesn't slide, but the backrest can recline.

Rear compartment climate controls are standard.

And top models get rear seat heating, side window blinds and a 220V socket.

Out back, rather impressively, luggage capacity isn't compromised by the Plug-in Hybrid battery, so it's the same 461-litre figure as the conventional self-charging RX Hybrid models - or 612-litres if you load to the roof.

There are some useful small compartments beneath the floor too.

With the rear bench folded (the backrest can be powered-operated with top-level trim), there's 1,678-litres of capacity on offer.

What about pricing? Well for this RX 450h+ Plug-in Hybrid, there's a step up of just over £5,000 over the equivalent self-charging RX 350h model.

We'll quote you RX 450h+ asking figures as they were from launch, in late 2022 and at the time of this test in early Summer 2023.

Prices for this PHEV variant start from around £67,000 and as with the RX 350h, there's a choice of four core trim levels - 'Premium Pack', 'Premium Plus Pack', 'F Sport Design' or top 'Takumi'-spec.

All 450h+ variants get the brand's E-FOUR 4WD system and Hybrid automatic transmission. All RX 450h+ variants come well equipped.

Expect to find LED headlights with Automatic High Beam, power-folding mirrors, roof rails, a powered tailgate, the 'E-Latch' electronic door opening system keyless smart entry, rear privacy glass, auto headlamps and wipers, all-round parking sensors, headlamp cleaners, a Thatcham category 1 alarm and a very complete portfolio of 'Lexus Safety System+' camera safety kit. Inside with all RX 450h+ models, you get a digital instrument cluster, powered steering adjustment, a 4-setting Drive Mode Select system, a heated steering wheel and Triple-Zone climate control.

Plus heated and 8-way power-adjustable front seats, a wireless smartphone charger and ambient cabin lighting.

Infotainment's taken care of by a 14-inch 'Lexus Link Pro Multimedia' centre infotainment screen with HD graphics, over-the-air updates, 'Apple CarPlay' and 'Android Auto' smartphone-mirroring and a 12-speaker DAB Premium sound system.

This display also includes a cloud-based embedded navigation system and comes with a four year data subscription package.

This derivative has a whole clutch of sector rivals who, at first glance, seem to use much the same engine technology, so you might not expect the same kind of efficiency advantage in-segment that the more affordable RX 350h self-charging Hybrid model enjoys.

Well yes and no.

The RX 450h+ has a smaller 18.1kWh battery than some of its competitors, hence a 43 mile EAER-rated range that's 17 miles down on the class leader in this respect, the Mercedes GLE 400 e.

With that Mercedes though, as with other similar PHEVs in the class like the Jeep Grand Cherokee 4xe, the Porsche Cayenne E-Hybrid and the Volkswagen Touareg R, the difference comes when you run out of EV range, as of course, beyond the city limits, you inevitably quickly will. At that point, in all the competitors just mentioned, you revert to a big thirsty petrol engine.

In an RX 450h+ in contrast, you revert to the much more frugal self-charging full Hybrid powerplant of the lesser RX 350h - which, as we've already seen, is the most efficient choice in its class.

That's why the RX 450h+ model's 25g/km CO2 figure all-but matches the emissions reading of a Mercedes GLE 400 e, despite significantly inferior EV range, hence this Lexus model's same low 8% BiK tax rating.

As with any PHEV, the RX 450h+ model's three-figure combined cycle fuel figure - here WLTP-rated at 256.8mpg - can be taken with a pinch of salt, but 35-40mpg as a regular reading should certainly be well within any owner's real-world scope. If you've stretched up to the RX 450h+ Plug-in model, you'll want to know about charging it.

Charging times are aided by a 6.6kW on board charger, which is why it takes only two and a half hours to replenish those cells from a conventional 7.4kW garage wallbox using a 230 Volt / 32 amp connection.

Connect up to a feebler power source like a domestic plug and you're looking at replenishment in 8 hours and 15 minutes - so still comfortably achievable overnight if, say, you happen to be away at a hotel or staying over with friends.

There's really nothing quite like an RX 450h+ in its segment.

And not only because its PHEV powertrain is uniquely based around a full-Hybrid engine.

This is a luxury SUV that feels expensive, despite the fact that it's better value than most of its rivals.

It's also difficult to better in terms of refinement, safety and media connectivity. Obviously, if you want an SUV in this class that prioritises sharp handling, a contender that's good for towing or one with a broad range of off-road ability, this Lexus isn't going to suit.

But assuming that you don't need to tick any of those boxes and you merely prioritise luxury, practicality and comfort, while wanting to improve your running costs, this RX 450h+ is difficult to overlook.

Even so, quite a few segment customers will.

Don't be one of them.