Just a note on Cecil’s column about downshifting. All the talk about the physics of cornering is great, but mostly misses the point. Use your brakes to slow down, whether on the track or on the street. (I assume the “racing” referred to is road racing, you hardly ever bother to shift on oval tracks. And on a road circuit you just don’t have time to use compression braking - if you are driving competitively you are on either the gas or the brake.)
For normal street driving, it’s not the cost of the clutch mechanism but the cost of the engine rebuilding that governs - engine work costs a lot more than brake pads or clutches. And it is the engine that suffers from excessive use as a brake, not the clutch.
On the other hand, if you are Juan Manuel Fangio and lose both the clutch AND the brakes in your Ferrari, and you STILL win the race (I forget where), then you really know a lot about compression braking, not to mention how to synchronize engine/tailshaft RPM. But few of us could do that.