World first! Driving Toyota's X-Runner

FOR most of us the first inkling that Toyota Australia had something special for the Melbourne motor show came on media day when the dust cover was ripped off the X-Runner.

But the dream for the local arm of Japan's biggest car company to do its own concept began in early 2002 and can be traced back to Toyota Australia president Ken Asano.

Inspired by the successful adaptation of the US market Avalon's underpinnings for Australia and its further development for use underneath the new 380N Camry, Mr Asano was determined to showcase the talents of his design and engineering team even more.

Hence X-Runner came into being.

Work on the third application of the local car-maker's Toyota Modular Platform started in earnest during August last year, overseen by Toyota Australia engineering veteran Peter Eustace, who holds the title of project manager commercial vehicles product development division vehicle evaluation and engineering.

Based out of the technical centre skunkworks at Toyota's Port Melbourne HQ, X-Runner's development began by stretching the TMP's wheelbase ahead of the rear wheels by 150mm.

A Japanese market RX300 off-roader donated its V6 powertrain, including constant all-wheel system with centre viscous coupling, three-piece tailshaft and four rubber mounts either side of the rear differential. A two-piece driveline was tested but found to transmit too much noise and vibration.

There is no traction control - although the new RX330, due here in April, employs a sophisticated stability control system - nor low-range gear ratios, which Toyota says was not required for a recreational application and would have added significantly to the project's cost and complexity.

While the supercharged V6 represents possibilities for Camry Sportivo (see separate story below), the adaptation of the all-wheel drive system similarly helps the case for building a cross-over as a third model line at the Altona plant in Melbourne, while the stretched wheelbase is being considered for the next Avalon to differentiate it further from Camry.

Avalon/Camry's MacPherson strut independent rear suspension was swapped for packaging reasons (to reduce rear wheelhouse encroachment in the utility's tray area) for the more compact live axle torsion beam from the Tarago all-wheel drive, which also donated its rear hubs.

Mounting the Avalon's front cross member in the RX300 subframe necessitated the re-alignment of the steering linkage, rear bank exhaust manifold and front stabiliser bar, which actually features fewer bends and therefore improved "value added value engineering".

"Dropping in RX300 powertrain and tuning the driveshafts was easy," said Mr Eustace.

"Accommodating it into the envelope was a bit tricky, however, especially the lower area where there's a transfer case."The tailshaft required exhaust system re-routing, while packaging issues saw power steering plumbing moved and the brake master-cylinder relocated to accommodate the blower belts.

While Avalon parts outnumber by far 380N Camry components, the remaining one per cent of X-Runner that did not come from Toyota's global parts bin was fabricated locally, including the exhaust system, front anti-roll bar, (modified RX300) fuel tank and new handbrake cabling.

With a rear spaceframe extension to support the composite body's rear tray, massive PBR brakes rotors and callipers, and a ride height that's increased by around 65mm (including the much bigger 19-inch wheels), X-Runner hits the scales at a substantial 1700kg.

Like heat shielding, however, weight has so far not been a priority in X-Runner's development.

"We've obviously got more things to consider for a production environment, like heat shielding the exhaust system around the transmission tunnel," said Mr Eustace.

"The basic architecture is there, it just needs massaging for the particular application."

Super V6 could power Camry

TOYOTA describes it as a VVT-i equipped and supercharged version of Avalon/Camry's 1MZ-FE 3.0-litre 24-valve DOHC alloy V6, but the X-Runner engine is more accurately identified as a supercharged version of the VVT-i V6 found in the RX300 donor vehicle and the Lexus ES300.

Either way, Toyota freely admits it is being considered for use in the Sportivo Camry, but the crucial item is the Eaton-type TRD supercharger, which is actually offered as a genuine Toyota accessory in New Zealand and has been considered for same by Toyota Australia's go-fast division T-CAM for more than four years.

T-CAM dyno tests indicate at least 185kW is reliably obtainable with the blower kit, with an undisclosed level of torque, but combined with X-Runner's freer flowing exhaust, chief engineer Peter Eustace says the figure is likely to be higher.

Of course, the new RX330, on sale here in April, employs a 3.3-litre VVT-i V6 producing 172kW in standard form, forming an even better basis for supercharging.

Mr Eustace could not reveal a torque rating for the all-wheel drivetrain, but when asked if a V8 was considered for application in X-Runner, he said: "Yes, but it may not have achieved what we were trying to achieve. It would have required major structural changes, such as moving the dashboard, but anything's possible."

DRIVE IMPRESSIONS:

WE'RE at Lindsay Fox's Anglesea proving ground near the Victorian coast south-west of Melbourne. This is also home to Toyota Australia's field engineers and the venue for our X-Runner drive.

Sitting behind the stitched leather dash in low-slung sports bucket seats and with two $4500 mountain bikes filling the rear-view mirror, I twist the key.

Under the watchful eye of the man who built X-Runner and another charged with transporting it and keeping it clean, a supercharged 3.0-litre V6 fires into a booming, lumpy idle that has only one thing on its mind - grunt.

I select D on the garden variety four-speed Avalon-style automatic shift gate and with a gentle brush of the right pedal there's an instant hit of monster truck-like torque.

Beginning at idle and showing no sign of slacking off even beyond 5000rpm, the wall of V8-style urge available from the blown V6 is enough to stretch the friendship with the four massive 245/45-section Dunlops.

Despite the impressive performance, the overriding sensation is one of solidity and stability, with an enormous level of traction and road holding afforded by an RX300-sourced, viscous-coupled constant all-wheel drive system.

While the big dose of typical Toyota ergonomics and build quality were expected, the impressive way the doors slammed closed with a dull thud was not.

Nor was the lack of refinement. Basking in the knowledge I was sampling the future in recreational all-wheel drive vehicles from Toyota Australia, my wry smile faded as the droning exhaust note overpowered my senses, the vibration of both internal and external plastics reaching a crescendo as I reached the Toyota-imposed speed limit of around 60km/h.

At least, I guessed it was about 60km/h.

See, the same one-off X-Runner (pronounced "cross" runner) prototype was actually designed to be a static show car, not a driveable vehicle.

Hence, the speedo and tacho did not work, the external (tray-mounted) DVD/internet monitor and concealed 240-volt transformer were in danger of shorting out if they got wet and the heavy steering did not self-centre.

The unsorted, long-travel suspension felt soft as it compressed under only mild cornering speeds.

Oh, and I was under strict instructions not to scrub out the unique, laser-cut Toyota logo tread pattern on the four special 19-inch Dunlop tyres because the car still needed to be shown at the forthcoming Adelaide motor show and, of course, in Sydney later this year.

There is, apparently, a fifth example of the wacky Toyota tyre, but it's in a glass case at Dunlop's Melbourne headquarters.

Despite all this - and the fact our first drive in the world's only X-Runner was its only real-road outing apart from a photo shoot at the same venue - the car is probably roadworthy save for the loud exhaust and lack of rear licence plate lighting.

So it is a testament to its engineering prowess that Toyota Australia's first ever concept car drove anywhere at all, really.

Which is what X-Runner is all about.

Designed to demonstrate Toyota Australia's engineering might for the benefit of both parent company Toyota Motor Corporation and the buying public, X-Runner is just one example of the company's ability to spin-off cost-effective derivatives from its Toyota Modular Platform.

Even as an under-developed show car never designed to be driven, not least by a Toyota outsider, X-Runner's relevance Down Under is obvious.

As a rolling exhibition of Toyota Australia's local manufacturing potential, it represents a serious challenge to Ford and Holden's all-wheel drive ambitions.