By Europe you are meaning Germany only, I believe, in most other European countries there is a speed limit of 130 km/h or 140 km/h, day or night doesn't matter:
Yep, but it doesn't change the "base" point, which is, you cannot legally drive faster than 120/130/140 kmh (depending on the country) and certainly NOT 180 kmh in any European country BUT in Germany (and only on some - many - strerches of the Autobahn, in some other there is anyway a speed limit of 120/130/140 kmh):
If you're driving through France or Spain after 1 AM you'll see see that everyone else tends to be speeding too.