but how do YOU know that the conditions are suitable for driving at 160Kph

I expected this replie, so I'll explain a bit.
My car is one of the more expensive models. Pushing it to 160 Kph is not pushing it's limits (200 Kph+ would be). 160 Kph still leaves enough headroom to rule out mechanical failiure because of pushing the car to (past?) it's max.

The road certainly wouldn't be closed to all other traffic, but I'm talking about the interstate (motorway) here. It's not like there are intersections, cyclists, pedestrians, ... there. Furthermore I specified that I only do this past a certain hour, say 23.00hrs or so. At that time there's almost no traffic on those roads. When driving 50km, I'll be lucky in passing 5 to 10 vehicles. (which are mostly trucks that ride at the first lane - keep in mind that these are 3-lane motorways)

The only danger I see is that I could hit an object on the road that fell off a truck or something. However, if I was riding at the legal speed (120 Kph) I would probably also hit it since the motorways aren't illuminated between 00.00hrs and 06.00hrs in Belgium.