I'm constantly surprised by how few people have heard of the "3 second rule".

The rule is simple and works for any traveling speed: pick any arbitrary mark on the road, watch as the car in front of you passes it, and count 3 seconds. You want at the very minimum, 3 seconds to pass before you pass that same mark.

This not only has the advantages described by the OP (he's definitely following it, if not calling it by name), but one thing he didn't mention is that it can save your life.

Why do car "pile ups" exist? It's because someone was driving along just fine, when suddenly they come to a crashing hault (at 70+MPH), and all of the tailgators behind them are not physically capable of reacting to the situation in time. SMASH! You're fucked.

Many people don't realize that, even if you can somehow stop instantaneously, you're much less likely to be hit from behind if you have time to gradually decelerate.

"only a fool breaks the 3 second rule" (takes roughly 3s to say)

Wouldn't that be "I pity the fool who breaks the two second rule"?

Except that this only gives you a linear amount of space with respect to your speed. You need space that goes as the square of the speed.

Depends. For cancelling your reacting time you only need linear speed. And if the vehicle in front of you has the some breaking deceleration as you can achieve, that's fine.

I use this rule too with a slight modification. I always try to keep an older vehicle in front of me and a newer behind me, without overtaking anyone if possible, in order to take advantage of the different braking distances of each.

Of course, if it's wet weather, you'll want to increase that - say to a 4 second rule.

I was taught to leave 1 car length per 10 mph of speed, which probably has about the same effect. Either way, I've been driving for a decade and haven't hit anyone yet.

I remember being taught more like 7 seconds, but that might have been for freeway driving.

The point of counting seconds instead of distance is that it works at any speed. People tend to keep the longest (time) distance at suburban speeds.

7 seconds at highway speeds can be over 200 meters.

I'm all for safety, but that is excessive.

If you break faster than most other cars will often get rear ended, it's not just cushion for you but also the car behind you. Try to break from 70 on an empty road after 2 second reaction time and see how long it takes and how far your car travels, and then consider what would happen if someone was tailgating you at the time.

PS: Thinking you have a 2+ second reaction time helps to cover when you are not directly looking at the car ahead of you. The less of that cushion you have the more you need to focus on the car in front of you.