Senior Moderator, Moderator: Community Buzz and Ambassador: Miles & More (Lufthansa, Austrian, Swiss, and other partners)
Join Date: Jun 2005
Location: 150km from MAN
Programs: LH SEN** HH Diamond
Posts: 29,514
If you are thinking of cash upgrades LH (in Europe anyway) charge the fare difference.
Y -> C upgrades with miles are not very good value. Much better to go for C awards if you have enough miles.