It is important to identify EXACTLY what model you are dealing with. The title says s320, but in the text you say s320l. The year is important also.
I have both a '94 S320, and a '96 S320, and BOTH of them have a switch on the console (forward and to the left of the shifter knob - US models) that control the outside mirrors. On both of these models, turning the switch so the arrow points 'down' (toward the rear of the car) allows you to retract (fold in), or extend (fold out), both the left and right side mirrors. Pushing the switch forward (extends the mirrors - fold OUT), or pulling to the rear (retracts the mirrors (fold IN).
This is all shown in the owners manual by the way (Page 11, item 32.
and page 60 - which also says to NOT force them OUT as it will damage the mechanism!)
Hope this helps,
Farrell