Sleeper, V4 is not a runway vacating point for runway 18R. It is a runway entrance for 36L. If the aircraft was trying to vacate at V4 then something had seriously gone wrong as the last opportunity to vacate would normally be V3. The LDA to V3 is something like 3200m. The Polderbaan is the longest runway at Schiphol with almost 4km of concrete.
I suspect that the crew were trying to vacate ANYWHERE (even V4) if it meant they would not go off the end of this very long runway!
http://www.ais-netherlands.nl/aim/06...AM-ADC-A2s.pdf