X3 Fuel Tank not even close to 67L worried

So today i decided to fill up my X3. which is normal if you want to keep the wheels turning. So I pushed the till the trip computes said I had Zero Range left.

So fill her up, the tank capacity is 67L I ended up putting in 86.5L[size=medium][size=x-large]!!!!!!!

WTF???

So how does this happen? I can think of only 3 things

1: The Tank leaks - but then there should be a dam under my car - so NO
2: The pump is worngly callibrated and I am paying to much
3: my X3 has a long range tank - I have done a lot of 4x4 'ing and I never heard of a long range tank for a X3

So how do I check or determine where the xtra 20L went
Here is some pics to prove this is no thumb sucking exercise