When the Lexus RX 450h was delivered to our little terraced flat in London, it felt like we'd been handed a temporary house extension, albeit on wheels. For this SUV — the largest in the Lexus lineup — is one big, distinctive beast that can easily cater for a family of five, plus shopping and extras.

At this scale, however, it doesn't care much for dinky on-road parking spaces. Conversely, it does care for city life: the "h" in its name designating its hybrid nature, combining a petrol engine with electric motor. So the RX 450h can handle electric-only EV city driving, giving it added eco points, while also boosting that 3.5-litre V6 engine as needed. It's not a plug-in, though, so no sockets or trailing cables; it recharges through regenerative braking and recouping energy from the engine when plausible.

Unlike many of it competitors — and there are a lot, from the German Audi Q7, BMW X5 and Porsche Cayenne, to the Swedish Volvo XC90 — the Lexus is luxe from the off, delivering oodles of tech and comfort without needing to tick a barrage of upgrade boxes. Sat behind the wheel all those surrounding buttons, dials and displays make it feel like navigating an eco spacebus. So is this slice of Japanese futurism the SUV to plump for?

In its fourth-generation guise the RX 450h is one good-looking beast, embodying the jagged, open-mouthed front grille appearance synonymous with Lexus's modern design language. We would much rather the Premier model, as reviewed here, offered the same morphed metal honeycomb grille as the Sport edition, but that's not the case — instead it opts for a more straight-laced and altogether happier-looking linear grille.

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Step around to the three-quarter view and Lexus's design language continues, with jagged imprints and almost folded metal panels giving an aggressive stance. There are no unnecessary bulbous additions, even to the rear, which although softer in appearance than the front, still has aggy-in-appearance rear lights. It's a distinctive overall look.

It's the details that really sell it for us, though. Those daytime LED lights, part of the Premier model, are bright enough to show a glimmer even on the brightest of days. The indicators aren't just boring flashing yellow bulbs either: their illumination motions from inside to out to show the direction of travel. We're almost surprised that nobody rear-ended us after becoming wildly distracted by them.

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The biggest problem with our review model? Someone, somewhere, for some reason, paid £645 to add a "Copper Brown" paint of coat. No, brown isn't the new black — it's just brown and yawnsome, almost like a counterbalance to the modernity of this SUV's otherwise enticing body shape. We'd rather have "Electric Yellow" or something, quite honestly — not that such a coat exists as an option direct from Lexus.

Step inside — and it's a step in, rather than a step up like in a Range Rover — and the Lexus RX is a wonderful place to sit on cushy leather-clad seats. There's even a three-level seat cooling system to cease any potential back sweats. Plus the stop/start keyless start button electronically slides the wheel down and into position, while automatically moving the seat forward for optimum pedal pressing. It's like readying a spaceship for launch, not sitting behind the wheel of a car.

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In the back there's a huge amount of legroom for passengers: we've driven plenty of distance with three 6-foot-plus family members on board without any problems. The seats follow the same comfortable configuration, and can be moved forward to allow additional for additional boot space length. Shame there's no seven seat configuration whatsoever though, unlike a number of SUV rivals. And as this is a hybrid there's not as much boot space as you'll find in non-hybrid rivals.

A 12.3-inch elongated centre screen above the dash dominates the driver's peripheral edge of view, which can be used to present in split-screen form, should you want to view, say, consumption alongside a larger navigation screen. The side bar splits nav, media, phone, consumption and climate; there is also a deeper main menu, which adds car, info and setup options into the mix.

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It all looks great, but it's actually a bit confusing and fiddly as heck to use. Lexus's Remote Touch Interface means a mouse-like controller is used to tour around the screens. It's terrible to use. Theoretically, it makes sense, but even after adjusting its sensitivity through the five available levels, we couldn't find one with enough nuance. It's a bit like driving one of those bikes where you turn left and it steers right; it just never feels right. All too often a centre option out of three would be bypassed for the other two, like a back-and-forth game of tennis with no winner. We've used the system a lot, having driven for around 10-hours non-stop over a long weekend, but despite getting more deft at using it we never came to genuinely like it.

But that's not all. There are some other details that could be better handled. The need to dig into menus to sync Bluetooth is a pain; the doubling-up of physical and virtual climate controls seems unnecessary; the limited physical button controls — menu, up/down, and sometimes-it-doesn't-do-anything back button — to navigate the system can't bypass the mouse-like haptic controller; and for all its tech, some of the basic on board plastic dials don't blend in with the otherwise high-tech appearance of the interior.

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However, the 15-speaker Mark Levinson audio system is stupidly good, delivering all the highs and lows you could want at considerable volume. Whether you're into classical, rock or burbling bass, the full frequency range is covered — including sub bass that we didn't know existed in some tracks. Add pseudo surround and it lifts things even further.

At the controls, sat in comfort, ears filled with top-drawer tunes, and — ignoring that mouse-like controller — it's a good start point to kick things into gear. The RX 450h's auto box doesn't run between gears in a straight-line fashion, which is a bit old skool in our view but works just fine, and once popped into "D" that electric-petrol combination is ready to roll.

Go light on the pedal and it does literally feel like rolling, too, with a near-silent gradual shunt away from stationary using the electric motor only. There's a dedicated EV button to put it into electric mode, should you wish, for city driving. However, given the sheer size and weight of this SUV, it's not especially happy to launch itself at speed using just electric power, so the petrol engine will kick in to combine and move things at greater pace if you press down that bit harder.

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A twist-dial to the centre tunnel, say above the EV mode button, can switch between eco, normal/custom, sport and sport+ modes, which tweaks how the car handles — although not by as much as you might think. The electric motor is always operational, whichever mode you choose. It's more the characteristic of the drive that's changed. Overuse the sport modes and it's easy to deplete the battery reserve, however, which will mean full EV mode becomes unavailable — and as there's no plug-in charging facility, it may be some time before ample charge has built up again.

This Lexus could hardly be accused of being super-fast, given its 7.7-second 0-62mph and top speed of 124mph, but in the real-world such figures become superfluous. Cruising along speed bumpy backroads and the RX 450h ate up speed bumps and pot holes like they didn't exist thanks to its air suspension. Hitting the speed limit down the M4 motorway, with the radio off, and there's only the tiniest amount of wind noise, making for a quiet and calm cabin.

Cornering, as you might expect from a vehicle over 5-metres long and almost 2-metres wide, is rather soft, and the turning circle akin to a private bus. Hardly a surprise, as that's the case with most SUVs, and one of the reasons Audi offers an optional feature to improve the turning circle of its Q7, for example.

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Economy is cited as 51.4mpg, which our driving — a mixture of short haul town and long haul motorway driving, using various modes — couldn't even nearly achieve, returning around the 31mpg mark and depleting the battery over the motorway stretch of driving.

So everything is soft and floaty; a bubble-wrapped drive that, ultimately, is all about comfort. And the RX 450h succeeds there, no problems, but takes things one step further on the tech-driving front with its cruise control options.

Using its front radar detection system, the click of a button activates Adaptive Cruise Control, detecting cars in front and maintaining a safe distance (which can be user defined between three distances — although everyone will always choose the closest possible setting, given how far it is). It even has active braking so will bring itself to a full stop in a traffic jam and, assuming the vehicle isn't stationary for more than a couple of seconds, continue to drive itself along after.

It's great to have both feet firmly on the ground, nicely rested, when doing a 3-hour jaunt from London to Cheltenham. This is about as self-driving as cruise control gets right now, much like Audi's Traffic Assist system, with the Lexus actually being gentler and more effective on the braking by comparison.

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The Lexus also has Lane Departure Alert and Lane Keep Assist, activated by pressing the correlating button on the steering wheel (it's a two-in-one). These act more as an advisory system, checking and visually confirming the car is in lane, providing a minor shunt back into lane if you begin to drift, while activating the vibrating steering wheel if you cross a lane without indicating. Again we'll compare to Audi's latest tech here, which has Active Lane Assist that will fully steer the car for you — being the more advanced and impressive option by a long shot (but, as we found in the Audi Q2, a mode too far that we simply switched off).

There's other tech to assist the drive. The head-up display (HUD) being a primary point, always in visual field of view to provide speed, cruise, sign readings and other active feedback. It's easy to read in all conditions without feeling like an interference — and if you'd rather have it off all it takes is the press of a button.

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When not going forwards, you'll praise the tech gods for implementing not only a rear camera, but also a top-down 3D visualisation setup that models the car's position in among its surroundings, making for a great park assist feature. Even the mirrors electronically angle themselves downwards to get a better look at kerbs, for accurate parking.

Shame this visual system isn't active when jostling between forward drive and reverse gears while parking, though, as its continued presence would be most useful, as we found out: a sticking-out kerb stone caught us while making adjustments going forward, and grazing 20-inch alloys against stone is never a good look (sorry Lexus).

Verdict

The Lexus RX 450h is a lesson in comfort. This SUV glides down city roads and motorways with ease thanks to its petrol-electric engine/motor combination, surrounds you in tech to make the whole experience even more comfortable — ignoring the horrible-to-use mouse-like controller system, anyway — and has enough distinctive exterior style points to stand out from the crowd.

The Premier model, as reviewed, might sound horribly expensive at a whisker under the £60k mark, but in reality that's on par with the Volvo XC90 and potentially less cash than a specced-out Audi Q7 (the e-tron hybrid model is anticipated to start from £65k — far more than the entry-level RX "SE" model).

As a slice of Japanese futurism, the RX 450h gets a bundle of things right, but it's the imposing competition that make its minor slip-ups all the more costly (seriously, that mouse-like controller system is just a no-go). Despite its high points, we're not convinced this eco spacebus gives Lexus enough edge over its Scandinavian competition, with the German competition putting a good run in too. Even though its Japanese styling will, frankly, turn heads all the more readily.