All I can say about Quattro is that it's awesome to drive. I routinely have fun taking off from red lights and leaving 4wd trucks sitting there spinning. It's full time power to all four wheels.. until a wheel loses traction; then the power distribution shifts to the wheels which still have some traction.
Here's a brief blurb about how Quattro works that I found on
<A target="_blank" HREF=http://www.audiworld.com/news/00/geneva/quattro.shtml>http://www.audiworld.com/news/00/geneva/quattro.shtml</A>
Quote:
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In the Audi quattro all four wheels are driven permanently. The advantage: in the ideal case each wheel needs no more than half the propulsive power required in a conventional single-axle driveline. Because the total force transmitted by each wheel - the aggregate of propulsive and lateral locating force - is limited, an Audi quattro can transfer a correspondingly greater lateral locating force to the road surface: a necessity for guaranteeing excellent cornering stability and outstanding straight-line running on both wet and dry surfaces.
Of course, an Audi quattro is particularly capable of demonstrating its traction advantage on wet roads, gravel and snow, on slippery surfaces or on partially iced roads. Conventional cars fitted with purely electronic control systems can also prevent the driven wheels from spinning. However, this method works only be reducing the propulsive force.
Not so in the Audi quattro, where the self-locking Torsen centre differential ensures that the engine's power is distributed uniformly to front and rear wheels. Any sudden differences in speed - for example if only the front axle hits a patch of black ice - sees the system responding like lightning: up to 75 percent of torque is then redirected to the wheels turning more slowly - in this case, the rear wheels. Torsen is a purely mechanical system.
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I gather it also does this not only front to rear but side to side.. you pay a price in extra weight for all the differentials, so they add a turbo and some nice stuff for added ooomph.. but I can still get over 30mpg on the highway. I can't say enough about how good this system is.. and I've tried the ones like Subaru, etc. There is a noticeable lag time in those that simply isn't there with Quattro.
