Re: Reality of q awd dry (long)

[dmiller@iea.com (Doug Miller)]

Scott,

I enjoyed your comments on the AWD vs RWD superiority and agree with most
of it. However, when you group street conditions with track conditions as
though they are the same, I must disagree.  On a track, the advantages of
AWD are muted and as you point out, various supercar tests show no
advantages.  My experience also shows this to be the case.  However, the
track is a smooth surface, relatively free of the large bumps inherent in
most street driving.

In a sense, the track is a "lab" situation with a controlled number of
turns and layouts and uniform surface, whereas the street is "real life"
and full of decreasing radius turns you've never negotiated, frost heaves,
gravel patches, and unpredictable drivers.

The advantages on the street would go to AWD due to the ability to cope
with a wider variety of situations at a higher throttle setting without
upsetting the vehicle's balance.  I have spent years evaluating prototypes
and production vehicles both on the track and on the road.  There have
frequently been times I've been impressed with a vehicle's handling on the
track during the day, then been disappointed while driving it home for the
night.  The Vette, for instance, is great on the track, but try carving it
through a high speed turn in a country road you've only driven a few times
before, at 8/10ths.  Those high frequency tar strips will quickly have you
dialing in all sorts of steering corrections.

Getting back to how the power reaches the ground, do that same curve at a
lower speed, but at full throttle and now feel how much more corrections
are needed. This is simply because the rear contact patches are getting
over 300hp, and suddenly unweighting them changes the amount of traction
they have (traction is heavily impacted by downforce - drag a pencil eraser
across a table. Now do it again with 5lbs of downforce).  If you were using
anywhere near the maximum traction the patches could generate, the drop in
available traction due to unweighting will have you getting crossed up real
quick.  Do the same manuever in a Mitsu 3000GT tt, also at full throttle.
Its power is split among all four contact patches, and that same situation
will have a muted impact, causing the fronts and rears to break loose much
less, and without the sudden spin. Now, and experienced driver could get
the speeds/times pretty close after 10 runs or so (as on a race track), but
remember I said you'd hit it with no advance warning.

Add in the zillion other surface variables encountered in a typical day
(gravel patch while pulling out of Taco Bell, frost heaves on that entrance
ramp, condensation on that manhole cover, snow, rain, etc) and AWD will
give you an improvement in day to day driving performance not captured on a
track. The harder you drive (the more often you're close to the adhesion
limits) the more often AWD will be in your favor.

I don't think you and I are too far off in our views, but for the road and
for the typical driver there are dividends to having AWD.  Perhaps we
should coin a new phrase to get out of this race conditions/street
conditions quandry and call what I am advocating "Daily dividends of AWD".

For instance, today I blew past a new 540i as he struggled up an icy hill
with his traction control chattering away.  Heh......

See ya,

Doug Miller
dmiller@iea.com