So what's a hybrid RX like to drive? Well you get in, luxuriate in the beautiful leather seats and enjoy the commanding SUV-style driving position before pressing the starter button to be greeted by.... nothing. The engine's running, true enough. It's just that at this point, it's doing so silently under battery power alone and if you've a gentle right foot, that's all it will continue to use at speeds of up to 30mph before the 3.5-litre V6 petrol engine kicks in, controlled via a six-speed CVT auto gearbox.
This mechanical package offers 308bhp and there's a useful 335Nm of torque for towing. It sounds quite good too, thanks to a sound generator system that creates a performance-style air intake roar. The E-Four 4WD system's functions have been tuned for quick response when accelerating through bends: there's no mention of off piste ability. Lexus doesn't think potential buyers will be interested - and they're probably right. As for handling, well other rivals offer a more involving drive. The RX is still one of the most comfortable, refined SUVs in its class though.
In creating this RX L, the designers were clear that the standard RX model's distinctive coupe-like profile had to be preserved. But look more closely and you'll notice that not only is the RX L longer at the rear, the angle of its tailgate has been made slightly steeper. That fine adjustment is actually important in making sure there's comfortable headroom for anyone sitting in the third row of seats. Even more valuable millimetres have been gained simply by moving the rear wiper mechanism from the top to the bottom of the window.
Raising or folding the third seating row can be done electrically with just the press of button. The rearmost seats are finished to the same high quality as the rest of the cabin and are comfortable for youngsters on long journeys and adults on shorter trips. The cabin is designed to be a social space, incorporating what Lexus designers call a 'lounge' effect that's open and light and where it's easy for everyone to see what's happening, share conversations and enjoy the in-car entertainment together on longer journeys.
List prices for the RX L 450h hybrid start at around £51,000 and there are 'RX', 'F Sport' and 'Takumi' trim levels. That's decent value compared to notable rivals like Audi's Q7, plusher variants of Land Rover's Discovery and 7-seat versions of the Range Rover Sport.
4WD is standard across the range and all RX models, as you'd expect, are very well equipped. Across the range, you'll find standard features like full-leather upholstery and powered seats, dual-zone climate control, rear privacy glass heated front seats, the Lexus Navigation system with an eight-inch display screen, a nine-speaker audio set-up with DAB, a reversing camera, LED headlamps, roof rails and dual chrome-tipped exhausts.
Across the complete range, Lexus Safety System+ is fitted as standard, providing active safety systems that help prevent or mitigate collisions in the most common traffic accident scenarios. Elements include a Pre-Collision System, Adaptive Cruise Control, Lane Keep Assist, Sway Warning System, Traffic Sign Recognition and Automatic High Beam/Adaptive High-beam System.
The returns on offer from the RX L 450h are virtually the same as for the five-seat model. So the WLTP returns on offer from the hybrid engine - 35.1mpg-37.3mpg and emissions returns from 132g/km of CO2 with 18-inch wheels fitted - look very good indeed. You're essentially looking at diesel-style running costs with cheaper green pump fuel, plus the kind of CO2 figure that'll really make a difference when it comes to the bottom line figure on your tax return.
Of course, much of the time - when you're waiting at a traffic crossing for example with the engine seamlessly disabled and battery power in motion - you won't be emitting any CO2 at all. Electric-only use doesn't just eliminate CO2 dirtiness: it also gets rid of NOx exhaust emissions too, green-friendliness today's government wants to incentivise. As a result, Lexus reckons that ownership of this car could save higher-rate tax payers a considerable amount when they compare this car against some of its less efficient diesel rivals. At the same time, the companies they work for will benefit from a handy 20% write-down allowance against tax.
An extra seating row can make all the difference. Having this Lexus in RX L form means that when you want a night out with friends for example, you need only take one car. Why wouldn't you? Otherwise, the reasons why you might want an RX haven't changed. This isn't the most capable luxury SUV you can buy. It isn't the sportiest to drive. And it's not the most affordable to buy. But despite all of that, it will continue to attract a significant following in this segment. Once you've bought the thing, after all, its running costs can be usefully less than even the most frugal of its diesel competitors.
While other manufacturers dithered over hybrid technology, Toyota's Lexus division got on and developed it. Their first hybrid RX was an impressive achievement and this one has added a more style and extra technology to existing strengths of comfort, refinement and a high specification. It's a tempting package - and in RX L form, now a more spacious one.