out of the owner's manual:
A - Automatic program
For economical driving. This is the initial
position each time the engine is started.
M - Manual program
This program is for driving conditions
under which the selected gear is to be
retained. The transmission then remains
in this gear both when starting off and
during acceleration. With this program
you drive only in 3rd gear in position D.
It is advantageous, e.g., on slopes or
when towing a trailer, to drive in selector
lever position 1 or 2, or in winter on
slippery roads in selector lever position
3, which enables gentle start