[nordify]

This is roughly how it works in Finland, although the maximum speed can be advertised. It works fairly well.

The real kicker is that the regulator has actually defined acceptable minimum speeds.

Minimum speeds can be stated either as an average or a range. Acceptable averages are at least 50% of the advertised maximum speed measured during any 4 hour period. If stated as a range, 40% of the maximum speed as a lower bound at any time is acceptable.

[doikor]

They are trying to up that 40% to 75% now.

http://fin.afterdawn.com/uutiset/artikkeli.cfm/2016/08/17/st... (in Finnish only though)