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I’m curious, why do you think that’s ambiguous?

What's ambiguous about it? Two meters behind a car at highway speeds can get you killed.

If it were a question only about cars at rest it would be phrased something like "how far behind a car should you stop when queued" or something of that nature.

There are few places in India where you can drive at "highway speeds".

This makes sense to me. What matters is the reaction time and braking distance.

I guess two meters is sufficient when you drive a walking pace, but any faster than that two meters will be too little. You say that this was in India, and I'm guessing two meters is way too much in a traffic jam :-)

"Two seconds" is what I learned too. The book here says that you should be at the spot where the previous car was two seconds ago, which is good advice, as it's independent of speed.

You can think of it as "it'll take you one second to react and one to brake to a stop, so you should be two seconds away".