firewalker

Oh really?
Perhaps that was true in the past and weight was a contributing factor in this. As better and more alloys are used, the weight differential between the two systems will decrease and will eventually be eliminated.
As the HP goes up and the AWD systems are further improved and finetuned, the quattro's and x's of this world will outperform RWD's; traction is traction, wet or dry. Already the new 535xi has better numbers than the 535i.

C's Bimmer

But from a straight line, the 535 has to be quicker. The AWD adds substantial weight to the car, over the standard 535.

KAF

Maybe, but don't forget the physics. You need traction at the wheels that are handling the power delivery.

Under acceleration the centre of gravity of the car moves further to the rear.

This loads extra weight onto the rear wheels and lightens the load on the front. (The opposite happens when you brake and explains why front brakes are normally more powerful than rears).

With rear wheel drive, the extra weight on the rear wheels provides greater amounts of grip and facilitates the laying on of the power.

With AWD the effect of lightening the load on the front under acceleration reduces the grip of the front tyres and reduces the benefit of the drive through the front wheels.

This is what happens in front wheel drive cars and why accelerating hard in one is not always a pleasent experience.

The perfect set up of AWD would enable the car to sense the movement of weight due to acceleration and cut the drive to the front, putting most of the power to the rear, only restoring power to the front when grip at the rear is lost due to road conditions.

This of course is only applicable under acceleration and the greater the acceleration the more pronounced the effect.

aybeesea

Hmmmm... I thought that's what Quattro systems did. They certainly do it (to an extent) in the X-Type.

http://www.modernracer.com/history/j...35history.html

ABC

bargamon

0-60 aint the end all. IF your running with the big dogs at 135mph and have a smile on your face your one happy customer.

In this country Audi is considered 2nd tier company.

You can bounce all the stats you want, but in reality 0-60 in the motherland does not rank as high as we think. The "GOT A HEMI?" attitude ain't what its all about.

Don't get me wrong, I love my 530i and its plenty fast.

Two factors drove me to BMW:

No manual transmission in an A6

and price consideration for lease.

This BMW inline 6 is a very sweet engine and in my opinion my configuration gives me great performance and value.

But, if I am approaching 150mph I'd rather have quattro under foot even if it take me just a bit more time to get 0-60.

At those speeds, stability and confidence are my preference.

KAF

So under full acceleration, 40% of the drive is still being transmitted to the wheels with least grip.

If we are happy the the front wheels never drop below 40% of the available grip then it works perfectly.

I don't know but I would doubt that is always the case, further development might well enable a better match between traction and powrer delivery.

So you are spot on, they do it to an extent.

sciarrino

I agree. And you have to consider also that in case of RWD (FWD just worse) looses grip, dsc breaks to not let the wheel spin = lost of acceleration.
Especially "fast" cars for would spin a lot when accelerating if not with dsc (or other names).