Not to mention that, in the country I live in, it is guaranteed that while you're idly rolling forward, some asshole will cut you off and take your place so that he can win that precious 2 seconds.
The linked article in this major thread explains why this doesn't make much difference:
http://trafficwaves.org/trafexp.html
In my experience cars are just as likely to cut in as out, and that's what the extra space is for anyway.
If you arrive any later it will be minute or two per hour, so worrying about people "getting ahead" of you accomplishes nothing. If you want to win the race against the others on the freeway tomorrow, leave 5 minutes earlier!
This happens to an almost comic degree in Boston. One car, invariably with Maine plates, insists on leaving five car lengths between them and the driver in front of them. By Boston standards this is a monster opening which is quickly filled and the Maine driver continues to back off. This happens the entire way through the city.