The Lexus RX has headline-grabbing emissions, but do they stand up to scrutiny?

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The first-generation RX — the RX300 — was introduced in 1998 and continued in production until 2004. The second-generation model was first shown at the 2003 Detroit motor show, and a year later Lexus used the SUV to launch its hybrid programme. The hybrid RX was first introduced to the UK in May 2005, with 195g/km of CO2.

Lexus continues to believe that hybrid technology is superior to diesel power for its cars. This is the third generation of its RX sports utility vehicle and the second to be offered with a hybrid powertrain. In fact, the hybrid version is now the only RX offered in the UK, in a market dominated by large diesel engines.

The hybrid is the only RX offered in the UK, in a market dominated by large diesel engines

Lexus’s persistence with the petrol/electric technology is driven by fewer particulate emissions and a smoother powertrain compared with diesel rivals. But if the headline figures for the new RX450h are anything to go by, class-leading CO2 emissions are on the cards too. This new RX450h has recorded 44.8mpg on the official European combined cycle, which makes its taxable carbon dioxide emissions figure just 145g/km. That’s not only substantially less than the latest Range Rover Sport TDV6, but also less than some superminis. That means it is eligible for a cheap tax disc and a low benefit-in-kind rating.

Your choice of RX trim levels comes down to two things: whether you want steel springs or air suspension and how much kit you want – although even the entry-level cars are reasonably specced.

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Lexus RX rear windscreen

On first encounter you could be forgiven for thinking the new Lexus RX is a facelift of the previous model, unless you saw the two side by side. Even then, Lexus admits it has maintained some continuity from the old model. It’s only 15mm longer, is 40mm wider, just 10mm higher and has a 25mm longer wheelbase. But the proportions are still similar; the cab-forward look suggests crossover rather than true muscular SUV.

It’s certainly a clean shape, as testified by its drag coefficient of just 0.32. The front grille, which follows the latest interpretation of Lexus’s L-Finesse design language, is more elaborate and recognisable than that of the previous RX. The angle of the rear screen, rearmost side window and bottom edge of the rear lights all match — a neat piece of design.

Not a great deal of its power goes to the rear wheels

One detail that’s more obvious in the metal than in pictures is the kink placed in the bottom of the rear doors. This helps to make the RX450h look less slab-sided, but cunningly also draws your eye to the hybrid badge.

The make-up of its powertrain is more crossover than proper SUV, too, because not a great deal of its power goes to the rear wheels. The RX450h has a complicated drivetrain. At the front is a 246bhp 3.5-litre V6 petrol engine, similar to the one in the previous RX but larger in capacity. It’s mated to a continuously variable automatic transmission and is assisted by an electric motor rated at 165bhp. 
These two between them drive the front wheels.

Meanwhile, at the rear there’s a second electric motor, rated at 67bhp, which supplies the rear wheels with additional power as needed. When all three engine/motors are giving their all, Toyota quotes a maximum power figure (it’s not as simple as adding all three together) of 295bhp.

For those who want a RX450h with more visual attitude, Lexus is offering an F Sport model. Aimed at the popular BMW M Sport and Audi S Line SUVs, the F Sport features a deeper, more vertical front bumper, with a mesh treatment on the upper and lower grilles. 19-inch wheels complete the visual makeover.

Underneath, the F Sport is equipped with a new lateral damper system. Rather than fixed bracing between the suspension towers, there is a single damper connecting them to reduce vibrations and improve stability.


Lexus RX dashboard

The Lexus RX450h’s cabin is one of its strongest assets. It’s a comfortable environment in which to spend time and has enough high-class materials and clever details to make the car feel suitably expensive. Excellent refinement – a result of a class-leading drag coefficient as well as the hybrid drive and quiet petrol motor – is also one of its biggest plus points.

A typical SUV seating position has the driver sitting high on soft, flat-cushioned chairs that offer a very broad range of adjustability. Forward visibility is also good, although the clever side and rear cameras are welcome for judging the car’s bulbous shape in tight parking spots.

The Lexus falls down on practicality - the boot is too small

Unfortunately, the main dashboard interface is less accommodating. The colour screen now sits higher in the dashboard, more level with the driver’s line of sight, but the fiddly Remote Touch computer-style mouse is an inconvenient way to control the car’s ancillaries. There’s a nice feel to the square joystick, which clicks when it touches an icon on the screen, but it’s more time-consuming and less intuitive than a simple rotating knob. Although most functions are also controllable from the steering wheel, this still seems like an unnecessarily difficult system.

The Lexus also falls down on practicality. Boot space with the rear seats up is just 496 litres – a good 120 litres less than that offered by the BMW X5. Even rivals with seven seats provide more room with the third row dropped, and despite the sliding rear seats that can fold 40/20/40 and also recline, buyers may be swayed by the extra practicality offered elsewhere.

Build quality is good, though, with quality materials used across the dashboard and door cappings. However, some of the switchgear – the electric window switches, for example – are a bit too Toyota for our liking.


Lexus RX V6 petrol engine

If we follow the badge logic, the Lexus RX450h should provide performance equivalent to that of a 4.5-litre V8 rather than the 3.5-litre V6 actually under the bonnet. With the Lexus’s total output of 295bhp, that claim looks a little doubtful next to the V8-powered X5, Mercedes-Benz ML, Range Rover and Porsche Cayenne, which each have at least 350bhp and some considerably more. And sure enough, our recorded 0-60mph time of 8.2sec confirms that the RX450h simply doesn’t have the performance to compete with the most sporting SUVs.

A fairer comparison is with the Volvo XC90 V8 and diesel rivals. The bottom line is that for the majority of driving the RX responds more than quickly enough for most people’s needs. Be gentle on the throttle when pulling away and the RX450h will move off under electric power only, and with sufficient juice in the batteries and a gentle foot it calls on the petrol motor only when speeds exceed 30mph. Ask for a more urgent getaway and the petrol motor kicks in earlier, and if you extend the throttle fully the rear motor lends a hand to give a turn of speed beyond what you could normally expect of a 3.5-litre V6 hauling a 2.1-tonne car.

The electrically operated brakes take a little getting used to

Other than boosting performance and fuel economy, the electric motors also allow hushed progress at slow speeds, but even with the petrol motor working the RX450h is impressively quiet, registering just 63dB at 70mph. Only under prolonged full throttle, with the CVT transmission holding the engine at high revs, does the RX sound stressed.

The electrically operated brakes still take a little getting used to, as does the regenerative braking of the electric motors, but the set-up is better resolved than that of the previous-generation hybrid RX.


Lexus RX cornering

First, a little background. The RX450h SE-L car we tested came with air suspension, but without the Active Stabiliser System (available only on the top-spec 
SE-L Premier). In our experience, this combination makes for a Lexus that works better in some situations than others. Its forte is long-distance cruising, where it is stable (the air suspension automatically lowers at speed) and rides comfortably. Somewhat surprisingly, it is also relatively nimble across country.

While the RX remains a car that’s unlikely to excite the enthusiast or threaten the X5 dynamically, this latest iteration is more agile than the model it replaces. The revised, quicker steering and additional rebound springs give a keener turn-in and a more controlled roll rate. What it isn’t, though, is particularly enjoyable to drive briskly, mostly because the electric steering is devoid of feel. Grip levels aren’t especially high from the eco tyres, either. But this shortcoming is unlikely to trouble many prospective owners.

The RX450h is at its worst in town

What may be of more concern is that the RX450h is at its worst in town. The first issue is the secondary ride; in common with other air-sprung cars, the RX450h is not the smoothest at slow speeds. The result is that ridges and manhole covers are more readily felt than they should be. Admittedly, the intrusions are well insulated from the cabin structure and the seats, so a jolt rarely becomes jarring, but the fact that the movement happens so quickly makes the RX feel unsettled. Steel-spung cars fair even worse.

The RX’s other downfall is that at slow to medium speeds it feels heavy and cumbersome. The problem stems from the steering weighting. At parking speeds it is light, which is fine, but as the speed rises above walking pace a concerted effort is required to wind on lock, making the RX appear more unwieldy than it actually is.

The F Sport, despite its revised underpinnings, doesn't entirely escape the inherent ride and handling problems of the RX. Good levels of composure and handling control have been improved upon but the town ride has suffered further, possibly due to the larger wheels.


Lexus RX 2009-2015

In comparison with its rivals, the Lexus RX450h offers impressive economy and emissions that promise to save money on fuel and tax. No one can dispute the financial benefits of the low CO2 rating; the RX will save a higher-rate taxpayer around £4000 per year compared with a diesel Discovery, while your company will also benefit from a handy write-down allowance against tax.

The reality of the fuel savings, however, will depend very much on how you drive. In our experience an average of 29.1mpg is realistic – still better than most diesel-powered rival SUVs, but not by the margin suggested by the official figures.

In our experience an average of 29.1mpg is realistic

The Lexus is also not cheap to buy; in popular near-range-topping SE-L trim it costs noticeably more than the equally well equipped Discovery TDV6 HSE and ML350 CDI Sport. Resale values tend to be a shade lower than rivals, too.

Even so, Lexus’s reputation for reliability and excellent customer service (they’ve made number one in the JD Power Customer Satisfaction Survey on numerous occasions), plus a comfortable and gadget-packed cabin, are sure to guarantee an ownership experience as hassle-free as any rival.

Every model bar the base model gets a decent sat-nav system (even if it is operated through the infuriating Remote Touch system), while top-spec cars get a stupendous Mark Levinson audio system (mind you, the audio in the other cars is pretty good, too) and LED headlights. There’s even a head-up display on range topping SE-L Premier models. In a break from the norm, Lexus doesn’t offer you a huge range of options for your car, preferring you to step up to the next grade and paying a fair few thousand for the privilege.


3.5 star Lexus RX

The Lexus RX450h is undoubtedly impressively refined at all speeds, not just when it’s driving on electric power alone. Its slippery shape and petrol engine makes it especially quiet on the motorway.

It’s more dynamic than its predecessor with a reasonable turn of speed and much improved dynamics. To our eyes, it’s marginally more stylish, too.

Quality and kit are strong points, although list prices are pretty steep

Quality and kit are strong points, although list prices are pretty steep – you have to delve into spec-for-spec comparisons to make a real judgment on value. Lexus dealers will also bend over backwards to ensure your satisfaction – something that can’t necessarily be said of rival retailers.

Crucially, the Lexus is capable of achieving class-leading fuel economy and emissions. While the reality is somewhat less than the 44.8mpg claimed by Lexus, the RX450h should prove as economical as a diesel SUV averaging closer to 30mpg in everyday use. However, every owner will benefit financially from the low CO2 rating, whether that’s as a company car user where the benefits are huge, or as a private buyer making a saving on the annual tax disc.

But when you look beyond the numbers to the RX450h’s credentials as a usable and satisfying SUV, its case looks weaker. For its footprint, the interior offers comparatively little flexibility or boot space. And although it has a reasonable turn of speed, it offers little for those who enjoy driving, while the low-speed ride is disappointing.

No doubt a hybrid SUV has its advantages, but conventional diesels still do it better.

Lexus RX 2009-2015 First drives