Pros and Cons of supercharging
Before turbocharging arrived in the 60s, supercharging used to
dominate the forced induction world. Supercharging, also called
mechanical charging, appeared in around early 20s in Grand Prix
racing cars in order to increase power. Since the compressor is
driven directly by the engine crankshaft, it has the advantage of
instant response (no lag). But the charger itself is rather heavy
and energy inefficient, thus cannot produce as much power as
turbocharger. Especially at high rev, it generates a lot of
friction thus energy loss and prevent the engine from revving
high.
A typical supercharger transforms the engine very much - very
torquey at low and mid range rpm, but red line and peak power
appear much earlier. That means the engine becomes lazy to rev (and
to thrill you), but at any time you have a lot of torque to access,
without needing to change gears frequently. For these reasons,
supercharging is quite well suited to nowadays heavy sedans,
espeically those mated with automatic transmission. On the other
hand, sports cars rarely use it.
The noise, friction and vibration generated by supercharger are the
main reasons prevent it from using in highly refined luxurious
cars. Although Mercedes-Benz has introduced a couple of
supercharged four into the C-class, they are regarded as too
unrefined compare with the V6 serving other versions.
The introduction of light-pressure turbochargers also threathen the
survival of supercharger. Volkswagen group, for example, dropped
its long-standing G-supercharger and chose light-pressure turbo.
Now supercharger is completely disappeared in budget cars, leaving
just a few GT or sports sedans which pursue high torque without
much additional to employ it. General Motors is perhaps the only
real supporter to supercharger. It offers a 3.8-litre supercharged
V6 for most of its budget mid to full-size sedans.
And from my fave source of info..
http://autozine.kyul.net/technical_school/engine/tech_engine_3.htm#Overview
From what I heard, Mercs are now switching to turbochargers (the
new A200 will use it and their new SL65 flagship is also
turbocharged). The SL65 is faster than the SC SL55
