How can a car with such gentle damping feel so tidy, respond so keenly, corner with such confidence, precision and sheer grip? It doesn't make sense. What I thought was about as incisive as a Lincoln Town car is attacking bends like a Subaru Impreza STI.
That will be the Super Handling All-Wheel Drive, then. It apportions torque where it's the most useful, which in itself is nothing new. But the degree to which it can do so is very new: according to the graphic just below the speedometer, the right rear wheel has just momentarily had the engine's entire output all to itself. (That trick certainly got rid of the understeer as I launched hopelessly enthusiastically into a tightening left-hander with another convenient bump.)
The secret is what happens at or near the rear axle. There's no rear differential as such, but instead each rear half-shaft has an electromagnetic clutch. If one slips slightly, more torque is transferred to the opposite wheel. If both slip, more torque finds its way to the front wheels. The amount of slippage is controlled by computer using the usual bevy of sensors: steering angle, lateral g, yaw rate and wheel speed.
But there's a special ingredient to SH-AWD: the speed multiplier, a device which takes the place of a centre differential in allowing a difference between front and rear axle speeds.
This epicyclic unit, just ahead of the rear wheels on the back of the propeller shaft, lets the rear wheels turn at up to 1.05 times the front wheels' speed. This seems an insignificant difference, but it's enough to ensure the rear wheels are always "loaded up" and able to transmit torque when needed - which is most of the time.
It also allows for the fact that in fast cornering, the rear wheels scribe a course of larger radius than the front wheels, so they travel further. So the stage is set for the Legend's amazing turn-in and its slightly tail-out cornering style. Most of the time the front/rear torque split varies between 30/70 and 70/30, but when needed either rear wheel can have up to 100% - as the dash display proved.
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| Airbags all around the Legend |
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What this system does is unique. One of its merits is that if it detects oversteer; it doesn't brake a wheel to put the Legend back on course, but instead accelerates the diagonally opposite one, so you don't slow down while the correction takes place. The only other car able to do this is the Ferrari F430 with its rear electronic differential - but that of course doesn't combine it with four-wheel drive.
