Fade from right to left

In AUDACITY 2.1.2, how do I make an audio track pan from right to left, eg making the sound of a car seem as though its moving across the channels. In this particular case its a mono track (same on L & R) and I thought of fading the right one out, at the same time as fading the left in, but Im not sure how to split the track to acheive it. Thanks

OK, Look in the track control panel.

If it says “Stereo”, like this: Audio Tracks - Audacity Manual
then click the downarrow on the “Track Dropdown Menu”. Select “Split Stereo Track”.

If, instead, it says “Mono”, like this: Audio Tracks - Audacity Manual
then click “Select” in the “Track Control Panel”, then Edit>Duplicate.

When done with your editing, click the downarrow on the “Track Dropdown Menu” of the top channel. Select “Make Stereo Track”. The top channel will become your left channel and the one below it will become your right channel.

Good Luck!

The current version of Audacity is 2.4.2 Audacity ® | Download for Windows

You could use this plug-in: Missing features - Audacity Support
Installation instruction for installing this Nyquist plug-in in Audacity 2.4.2 are here: https://manual.audacityteam.org/man/installing_effect_generator_and_analyzer_plug_ins_on_windows.html#nyquist_install

If the track has two channels, then the above effect can simply be applied to the track.
If the track has only one channel, then you will need to duplicate the track and then join the two tracks to make a “stereo” (2 channel) track first.
See here for how to split and join tracks (in Audacity 2.4.2): Splitting and Joining Stereo Tracks - Audacity Manual