I think I know now why Voice_TTS-svox-dut-f1-lua.zip does not work in the car.
Car Android is v 6.0.1 and I cannot update Vocalizer tot version 3.7.2 while my tablet is Android 10 ( Vocalizer can update to 3.7.2 )
Latest version in the car I can use is v 3.4.3
Google Play says min Android 7 and higher for version 3.7.2
That's the only difference between tablet and car I can think of.
Still no idea why that voice does not play and the other does, there must be some difference between them .