Here's two shots. One of is of the drivers main console, the other is
one of an unadorned Flexity at Willy-Brandt-Platz, home of the European
Central Bank. (There is a giant Euro symbol in the park here).

Over half or more of the trams I saw in Frankfurt had advertising on
them - mostly just panels under the windows, but also a few 'all over' jobs.

The city is basically running two sorts of trams - Duewag low floors,
3 sections, 3 trucks (one under each section). Appears to be 40 of
these.These are 'R' class.
There appears to be 30 Flexities, 3 sections, 4 trucks, centre section
rides on two trucks. Designated 'S' class.
I saw other makes of tram only on weekends in 'Heritage' service.

The 'U-Bahn' line, U5 'turns into a tramway' (stadtbahn) above ground.
The cars that run this route are older high floor cars with moveable
steps. When running underground in the city centre they have level
boarding at high platforms. When stopped in the street, part of the
floor next to each door folds down to make a set of steps.

Lines U1/2/3 run down the middle of streets as well, but in a fenced
off centre reservation and have high platforms - but many many level
crossings. (Each cross street, extra pedestrian only crossings)

So I think I can say where the 'Adelaide S class Flexity' thing came
from though it's disputed that Trans Adelaide actually called them that.
They are according to a 'cardboard' tram kit I got at a Museum they are
'Die neue S-Klasse Niederflur Straßenbahn.', which could be translated
as 'The new S Class low-floor tramcar'. So there will be documents
floating around Adelaide that make reference to them as S class trams as
they are copies of the Frankfurt S Class tram.

I have many many more photo's of them. In a few weeks I hope to be
able to put up the entire collection on my web site. I just have lots of
sifting to do.