I fill mine with the handle at the 12 o'clock position! Seems to be a lot better though.........
Presumably those people with 1980's plus 8's which had twin fillers didn't have a problem??

1969 4/4
1995 plus 8
1996 Plus 4 4seater
2002 Aero S1
2013 M3W
2014 Plus 8