Re: What's the point?
Sorry I missed this at the time, but would like to respond (late as it is :) )
apropos your comment re reaction time, surely, if you are relying on someone's brake lights to tell whether they are slowing or not, then in my opinion, you are driving far too close.
What happened to the "being able to stop in 1/2 the clear distance".
I hope that you are not following me if you are relying on my brake lights.
The example I quoted is where someone is riding their brakes - tapping/pressing the pedal enough for the brake lights to come on but not actively slowing down. I've seen cars with a faulty/badly adjusted brake light switch where this same effect is visible. Another you may've seen are those with the bright "rear fog gaurd" lights that 'drown out' the brake lights in red noise. Either way, the situation is the brake lights are on a lot and give no indication to how fast the driver is slowing.
After a lot of these, especially if it is someone who thinks you're following to close (IMO in which case you are, back off some more!), you can become accustomed to seeing their brake lights come on without any clear reason (they're not slowing for corners or hazards, they're just flashing their brakes). When for some reason these people do brake much harder
You know NZ's scenery. How often have you seen someone (often a tourist but not always from o/seas) suddenly brake hard in a highway without warning because they've just spotted a pretty waterfall or cute bird or something? No turn offs, no other traffic, just this person unexpectedly braking hard. Again, it can be hard to judge their rate of deceleration especially if there's a corner approaching and your first inclination is that they're slowing for the corner, not braking to a stop.
It takes our brains a moment to assess a situation and react. If our assessment is off, which is easy to do, then what may've been a 4-second following distance at 100kph can very quickly become an "OH FUCK moment when someone does something unexpected. When the situation started I may've been able to stop in 1/10th of the distance ahead but if I mis-calculate their actions you can run out of space quickly.
I don't just rely on brake lights, but often they're one of the first indicators someone is slowing. When someone just takes their foot off the gas, following drivers don't have a way to see you're slowing until the rate of closure gets fast enough.
PS, I've been well known in NZ circles for promoting "If in doubt, stretch it out" - good following distances are something I believe the cops should be harder on. My bike can easily out-brake your car, in when bad stuff happens the last thing I want is to have to think of what the person behind is doing as well as the stuff happening in front/beside me. The biggest asset you have when driving is time - time to see, choose an action, and act - time to stop if needed, or pass, or change lanes, or pull off and take a break/calm down. If I have concerns about the nature of the road, I start giving myself extra space. This does tend to antagonise any idiot following me (and we see far to many of them on Kiwi roads), but means we'll get there without worse incident.
And yes, I often drop down a cog or two in readiness for things happening a few seconds ahead. Like the comment you replied to where I talked of the front being "loaded" (weight transfer etc taking place) due to automatic systems, I sometimes also like to do much the same to the rest of my drivetrain - engine is already at higher RPM, clutch engaged, gears engaged, all that's needed is a stomp on the gas.