Porsche 911 Carrera Owner's Manual page 127

Select "Intermediate time" with the operating
lever and push the operating lever forwards.
The intermediate time will be displayed for approx.
5 seconds. The on-board computer display then
returns to the "Stop timing/Intermediate time"
selection.
You can stop the stopwatch or measure
another intermediate time.
In order to start timing a new lap:
The "New lap?" selection appears for 5 seconds
after selection of "Intermediate time".
Select "New lap?" with the operating lever and
push the operating lever forwards.
Controls, Instruments
125