Originally Posted by
zorn
It turns out the lowest status miles earning fare is L. It also turns out that fare is upgradeable using a SSWU. So, using AC.com, select the "Display only fares eligible for upgrade" option.
'A' class, when it exists, is lower than L and also earns status miles.
The tricky part is that I think there may still be some routes where A fare exists and earns 100% status miles, but is not upgradable and therefore would escape detection via
Zorn's Transformation. I know A is definitely upgradable on France/UK, but I'm not sure if this is also the case with Germany, which doesn't have the branded fare classes (Leisure, Latitude, &c) yet.
I may simply be imagining this last part, so don't go by what I've said until someone more authoritative corroborates it !