i am fairly sure there are differences between summer and winter fuel in Germany (and the UK) since I remember reading reports some yars ago about the addition of ethanol and tests of RVP. I guess that since Germany is a much smaller land area than the USA there is one national vlaue that is used rather tahn regional variations.

another guess is that there are EU regulatuions and standards.

Here in Yurop, Reid Vapour Pressure is expressed in kPa

For any of you who are preparing prudently (not hoarding) both the RVP and octane rating will fall over time.

You would think so, from a technical perspective at least, but this concept was completely unknown to the fuel distributor, including the idea of making sure to buy the correct blend of gasoline to store. Germany is not really a place noted for wide ranging curiosity, so it is possible that his not knowing about it merely reflects the fact that only people that really need to be concerned are those at the refinery.