We like
Torque, economy, car-like road manners

Room for improvement
Minimal rearmost luggage space

TOYOTA quietly slipped a four-speed automatic transmission into the options list for its turbo-diesel Prados for the 2001 model year. At the same time, it added stability control and traction control to the top of the line Grande and VX models. All this makes the medium-size off-roader a complete package, with engine and transmission options to suit just about everybody.

The medium-size Prado hit the mark with increasingly urban 4WD buyers via its easy handling and more compact dimensions than the full-size LandCruiser. Yet it remains effective off-road with a dual-range transmission and the sort of underbody clearance needed to negotiate bush tracks deep in the mountains.

The 3.0-litre, four-cylinder turbo-diesel was introduced during 2000 and added a more rugged dimension to the Prado. It is strong on torque with a solid 343Nm wound out at just 2000rpm. This means it has the most torque in the Prado range, significantly stronger than even the 3.4-litre V6.

It is not quite as beefy in a competitive sense as Toyota would have you believe, though. The smaller capacity five-cylinder turbo-diesel in the Mercedes-Benz ML270, for example, thumps out a staggering 400Nm - at just 1800rpm - while the new Nissan Patrol 3.0-litre, four-cylinder turbo-diesel produces 354Nm at the same 2000rpm as the Toyota.

The turbo-diesel is of basically simple design, contrasting to the common-rail, direct injection, multi-valve, twin camshaft technology employed by some other manufacturers. The engine uses an iron block, alloy head, single overhead camshaft design with two valves per cylinder, twin balance shafts to reduce vibration and electronic fuel injection using a fly-by-wire throttle.

The water-cooled turbocharger operates through an air-to-air intercooler for combustion efficiency and the injectors pulse fuel into pre-combustion chambers. Torque output is assisted by the relatively pronounced long-stroke design that sees a bore/stroke configuration of 96mm/103mm.

Toyota says the new engine is low in emissions with carbon monoxide levels at 1/20th of the level specified by Australian Design Rules, and hydrocarbon emissions at one fifth of legal requirements. Toyota does not talk too much about the typical diesel smoke output, but does say it easily passes legislated requirements.

And naturally the turbo-diesel picks up the usual fuel economy advantages. It is the most economical of all Prados and with a capacity of no less than 159 litres, there are many places to go on just one tank of fuel.

Changes to cope with the extra torque of the new engine include a new, heavier-duty clutch and a bigger radiator.

On the road, all this translates to a nicely responsive diesel Prado, not particularly loud and relatively smooth with the twin balance shafts. It operates more quietly than the Holden Jackaroo turbo-diesel, but is not as hushed as the Mercedes.

Some of the noise control is no doubt due to an interesting double-skinned bonnet that channels air from the grille area to the intake system, doing away with the often-used trademark bonnet scoop signifying that something turbocharged lies within.

Initially the turbo-diesel was not available with an automatic transmission but now is, and this only widens the appeal of the economical oil-burner. The auto will use more fuel than a manual version, but economy remains a strongpoint.

As is usually the case with turbo-diesels, being hooked up to an automatic transmission makes a positive change to the vehicle's character. The turbo-diesel's strong torque plays a major part in the compatibility with the automatic gearbox. Automatics are generally better able than humans to read the optimum change points for diesel engines, so acceleration is strong. The auto kicks down readily enough, too, making quick work of passing slower traffic on the open road and compensating for the slight lag that occasionally catches the Prado out in manual form.

The adoption of what Toyota calls "Swerve Control" in the Prado is another step towards bringing the dynamics of a large 4WD closer to those of a regular car.

Toyota's swerve control works the same way as other stability control systems, applying braking on individual wheels when required to restabilise the vehicle if it is moving into an understeer or oversteer situation. A muted but urgent beep tells the driver that the system has just stepped in.

The traction control system now fitted to turbo-diesel Prados uses much of the four-channel anti-lock braking system to detect wheelspin at individual wheels and applies a slight braking force to the slipping wheel to redirect torque to the wheel with more grip.

In practice, the system works well, flashing lights on a pictogram built into the instrument panel to tell the driver how busy it is. But it is no substitute for engaging the centre differential lock to ensure steady supply of power to the front and rear ends when the going gets really slippery. It is at its most effective on a dirt road or wet bitumen.

In fact it is on the road that the Prado really shines, with a comfortable ride provided by its all-coil spring, double wishbone front, live rear axle arrangement. Its road manners tend more towards those of a car than some of the larger wagons. The Prado might tend to look slightly high and narrow, but from the cockpit it feels secure and is helped along in no small way by the security of the full-time 4WD.

The steering system is well weighted and responds accurately to driver commands. It also offers a relatively tight turning circle for a 4WD of 11.4 metres.

The Grande turbo-diesel is comprehensively fitted out, from its leather upholstery, power front seats, power glass sunroof, six-disc CD stacker and dual air-conditioning system.

The inclusion of stability control, anti-lock brakes with brake assist and traction control adds almost unbelievable refinement to a sector of the market that was once barely removed from utilitarian delivery vans.

The days of rubber floor mats, manual locking front hubs and bar-tread tyres are well behind us.