Towering, status-enriched 4x4 accelerates to 62mph in 7.6sec

Frankly, ‘H’ is an awfully innocuous name for what has to be the world’s most complex production car and, arguably, right now the most interesting, too. ‘Lexus RX400h’ doesn’t exactly punch its weight when you consider the significance wrapped up in that little letter.

As you’ve probably guessed, it stands for ‘hybrid’ or, in Toyota/Lexus speak, ‘Hybrid Synergy Drive’. Nothing especially new here, of course. The Toyota Prius uses the petrol/electric combo powertrain and, remarkably for such a plain-looking family hatchback, has augmented strong sales to the general public with an unprecedented level of celebrity endorsement on the west coast of America. Apparently, it’s a lot easier to spot the stars in Hollywood these days: they all drive Priuses, no doubt in the hope of proving that you can lead an extravagant lifestyle and save the planet at the same time.

Their collective sigh of relief at the launch of the RX400h must be audible on Sunset Boulevard, though. How many, I wonder, will insist on continuing to be seen in the Prius when they could be driving the world’s first high-performance hybrid SUV? This time, what Lexus calls ‘brand-defining technology’ has delivered the real cake-and-eat-it deal.

It comes in the shape of a towering, status-enriched 4x4 that accelerates to 62mph in 7.6sec and has a top speed of 124mph yet returns 35mpg on the combined cycle and posts a jaw-droppingly low (for a full-sized performance SUV) 192g/km carbon dioxide emissions figure. To put that into perspective, a turbo-diesel Land Rover Discovery TDV6 has a 0-60mph time of 12.2sec, does 27.2mpg and produces 275g/km of CO2. Never has the predatory green anti-SUV lobby been quite so wrong-footed by its prey.

The sales potential of the RX400h is massive. Target sales in the UK for the remainder of 2005 are 1625. Orders placed in the US alone currently stand at 18,000 and counting. In 2006, the RX400h is expected to account for half of all RXs sold. And when you take a closer look at what you get for your money, it’s hardly surprising.

Three engines for a start. If you think the way the Prius organises its single petrol and single electric motors to achieve the most efficient team effort is a small miracle, the RX400h’s effort amounts to the full parting of the Red Sea number. It employs a 208bhp 3.3-litre V6 petrol engine and not one but two electric motors – a new and impressively brawny 165bhp unit in the front and the Prius’s 66bhp motor at the back, answering the part time 4x4 brief.

But don’t be tempted to add up all the outputs and conclude that the RX400h can call upon 439bhp. It doesn’t work like that. ‘Synergy’ is the key word, here. In normal driving conditions, the petrol engine’s power output is divided by a power-split device, both to drive the wheels directly and also to power a generator which, in turn, drives the electric motors and simultaneously charges the battery beneath the rear seats. The allocation of power is constantly monitored and adjusted between the petrol engine and the motors to maintain the highest efficiency, not the highest output. The best the RX400 can manage is 269bhp. During deceleration and braking, the petrol engine switches off and the electric motors act as high-output generators.

For the driver, things could hardly be simpler. Climb in, twist the key (no starter motor, not much noise of any sort other than a faint background hum), pull the gear selector into Drive and, well, do just that. If you’re fairly gentle with the throttle, you’ll pull away in something approaching eerie silence as, unless the battery reserve is low or you need to blast Tom Hanks in his Prius away from the lights, the RX400h always starts using electric power alone. And it will always return to it whenever possible. When stationary, it shuts down altogether which, of course, is zero emissions in the truest sense. If the Lexus RX weren’t already the quietest SUV on the planet, it is now.

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Osamu Sadakata, chief engineer for the RX400h, describes the driving experience in one word: seamless. ‘Every part, every movement must be seamless and the handling so smooth that the driver remains unaware of the sophisticated technology at work. I like to think of it as unnoticed technology’, he says. And he’s right. The biggest contribution to the impression is the way the engines and continuously variable transmission co-operate, not just to make acceleration truly stepless but also to fill in what would otherwise be troughs in the power and torque curves. Perhaps the most startling first impression is what happens when you pull out to overtake. Yes, as your toe goes down, the engine revs flare in the way common to all CVTs but instead of the road speed being slowly dragged up to match, there’s an instant and very solid thump in the back – accompanied by a twitch of torque steer – as the petrol V6’s exertions are manfully assisted by an injection of electrical twisting action.

Lexus’s choice of Greece as a launch venue for the RX400h offers a handy juxtaposition of choked and choking city driving – a legitimate RX400h environment, though it seems unlikely it will qualify for the London congestion charge exemption granted to the Prius – and smooth, snaking coastal roads. At one point, on the journey from Athens to our hotel, we’re overtaken by a Merc SLK 350 in a reasonable hurry. Despite enjoying the scenery and the remarkably hushed, comfortable progress of the Lexus, we decide to be in a reasonable hurry, too. Just to see.

The first point about the RX400h, says Lexus, is that despite its excellent environmental credentials, it really goes. The second is that although an SUV will never handle and grip like a sports car there is much that can be done to prevent it taking an unintentional trip into the undergrowth. In the RX400’s case it’s called VDIM (Vehicle Dynamics Integrated Management), a kind of chassis dynamics Big Brother that co-ordinates the anti-lock brakes, electronic brake force distribution (EBD), traction control and vehicle stability control to keep the thing in shape and safe when you’re pressing on. VDIM triggers the appropriate systems when it detects the vehicle is nearing the limit rather than when the limit has been breached, with the aim of maintaining control more smoothly.

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The effect all this has on the briskly driven SLK is remarkable, its course through bends becoming progressively more ragged as the RX400h – leaning over at increasingly improbable angles while clinging to the chosen line, and more or less its equal down the straights – refuses to budge from its tail. This, it should be said, is sport rather than fun. The RX400h is at its very best being a Lexus: comfortable, refined and effortless. The hybrid technology only enhances these qualities, never more so than when it’s purely electric. You’d be fooling to attempt any serious off-roading in this car but expect Hollywood to be overrun in the coming months. The SUV has just booked its ticket to the future.

Matt Prior

Matt Prior
Title: Editor-at-large

Matt is Autocar’s lead features writer and presenter, is the main face of Autocar’s YouTube channel, presents the My Week In Cars podcast and has written his weekly column, Tester’s Notes, since 2013.

Matt is an automotive engineer who has been writing and talking about cars since 1997. He joined Autocar in 2005 as deputy road test editor, prior to which he was road test editor and world rally editor for Channel 4’s automotive website, 4Car. 

Into all things engineering and automotive from any era, Matt is as comfortable regularly contributing to sibling titles Move Electric and Classic & Sports Car as he is writing for Autocar. He has a racing licence, and some malfunctioning classic cars and motorbikes. 

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