This has been covered in another post on this site.
Ford have stated that there should be no problem associated with the filler cap/neck with regards to syphoning etc.
This system is fitted to all the newer Ford range of cars - ka, focus, fiesta, etc.
Ford claim that they have not had any reported issues with it so far, as the internal sprung cap should be sufficient to stop syphoning happening
Robert use this link to take you to fuel capless fillerwww.bmaxownersclub.co.uk/.../easy-fuel-
<b style="color: rgb0, 128, 0; font-family: Arial, sans-serif; font-size: 13px; line-height: 19px;">cap[/b]less-system_topic192.html