Brian-Gaff wrote:

The issue with these is that the quality is pretty naff

More naff than the FM transmitters? I've seen a few people say the reverse.

and the motors in the cassette run all the time which is very
wasteful.

Only the same as playing an actual cassette and compared to the power of
the engine, not even worth thinking about.

the fm stereo way sounds best if set up properly

Depends on finding a station (and pirate) free chunk of VHF spectrum,
and maybe having to retune on long journeys to find another. The fact
that these often have mono/stereo settings in the transmitter tends to
imply the stereo modulation isn't the best, either.