Re: quattro-digest V4 #1596

[Dave Eaton <dave.eaton@minedu.govt.nz>]

given the recent discussion about awd vs rwd handling, i thought that i'd copy
the anaylsys which 'car' magazine did of the top 3 german sports sedans, the m3
(evo ii, 321hp, rwd), and the new amg mercedes c43 (4.3l 306hp v8, rwd) with
the new audi s4 (265hp awd).

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"Maximum grip versus big slip"

"The M3 looks to hold the aces, not least because it's the only car of our trio
able to corner sideways to order.  But though the M3 is benign and sure-footed
in the dry, it loses its tail much more suddenly in the wet, and can be very
tricky to catch.  That makes it a bad choice for slippery conditions, because
there's no traction control.

"Smaller and lighter than its rivals, the BMW has beautifully responsive
steering with ample feedback and minimal interference.  It's quicker to respond
than the AMG's helm, if not quite as quick-fire as the S4's (geared at just 2.6
turns lock-to-lock), and it points with reassuring accuracy.  Yet this is a
very stable car, even when you let all 321 horses out at once.

"The roadholding may not have the quattro's magnetism, but the tyres hang on
well and the balance at the limit is a delectable dialogue between steering and
throttle.  From a go-fast, fun-to-drive, explore-your-own-frontiers point of
view, the M3 is the car to beat.

"On real roads, though, the S4 squeezes ahead of the M3.  And this marginal
lead increases if the road turns wet, because the S4 stays neutral where the M3
has already started to slither.  Of course the S4 has its limit, too, but it
arrives with a subtlety which lets you dial in speed adjustments in small, safe
doses.

"The S4 is a natural understeerer, but you can rein it in by reducing throttle
opening and steering lock.  Voila - now the Audi is ready to execute a perfect
powerslide.  With all four wheels in drift mode, the S4 strikes an intriguing
balance between slip and grip, while remaining totally controllable and
deflecting no more than a tame angle from the intended direction of travel. 
The Audi's steering is the lightest in this group, and not as communicative as
the BMW's, but it suits the S4's personality.  While te M3 calls for active
interplay at the wheel, the 4wd Audi is at its best if you apply small steering
inputs and keep mid-corner corrections to a minimum.

"You're feel more vertical body movements in the S4 than in the M3, but its a
side effect of the added compliance that's part of the Audi's more forgiving
character.  And thought the S4's brakes aren't the most powerful (this accolade
goes to the C43), they're so beautifully weighted and so perfectly balanced
that late braking becomes habit forming.  This is a wonderful car for bad days.

"And the C43 AMG?  It has all the ingredients of a handling champ: big, brawny
V8, sophisticated chassis, wide tyres.  But it also has ESP, or Electronic
Stability Programme.  Another interpretation would be Eliminates Sporty
Performance.

"ESP employs a handful of sensors to keep that fat rear end from unruly
behaviour.  The limit deemed safe by the chips may be approrpiate for the tall,
undertyred C180, but it's nonsense for the AMG.  With the warning triangle
flashing furiously, the electronic throttle and the brakes interfere long
before their act is due.

"Even with ESP switched off, the electronic traction-control system (ETS)
remains active and prevents the rear wheels from lighting up by applying the
brakes.  As a result, the Mercedes indulges in early and determined understeer,
spoiling both the cornering speed and the driving pleasure.  It's made worse by
steering that's too heavy and slow to inspire the driver.  The brakes are truly
impressive, however, and the ride's absorbency is remarkable.  It suits this
high-performance office on wheels perfectly.  There's huge talent lurking in
the C43's chassis.  It just needs a little more teasing out.
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