The simplified distance rule we learn in europe is: half your speed (km/h) in meters or as an equation, v/2000. E.g. you drive 120km/h, keep 60m distance.
I've always preferred the 2 second rule. You don't need to do distance math in your head, just find a tree and count the time it takes to get from their car to yours.
Ah, that could be interpreted at least two different ways. I have a suspicion of how this conversation will go, but I'm interested to find out.
It's my opinion that the metric system is superior to the imperial, so we should all be primarily exposed to the superior system. Some may disagree and I won't claim that I'm objectively correct. No worries if you disagree - regardless of my opinion, the imperial system is what I've been exposed to and what I use.
Alternatively, the statement might be interpreted as "you should be familiar with the metric system even if you reside in a country where it's not the primary system." That's probably less true - while it might behoove one to be familiar with the metric system, I don't blame the individual for the limitations placed on them by the government, regardless of what's better.
If you have a third interpretation, it's probably not what I meant, but I would be interested in hearing it.
Judging by how close people follow me on the Interstate, I have a feeling most drivers think this but only a small percentage can do it effectively.
And judging by how close 9 out of 10 pickup truck drivers follow tailgate me on the interstate even when I am doing 10-15 over, I have a feeling most don't care and would prefer to run me over in their lifted Rams and SuperDutys.