Ya see
@JonnyG, that's where I've been going wrong!
My finger tips, for the vast majority of the time are bone dry!
Partly because I hate leaving finger prints on the screen and partly because I'm still in the habit of applying hand gel every 5 minutes.
Anyway, I had always assumed that the touchscreen working was to do with the electrical current being generated in your body, then being detected by the screen?
So the quality and cost of the components will definitely impact performance.
As per my comment up above, my phone never misses a touch and works perfectly.
But my phone was expensive.
The screen in the car was not.
I don't have an issue with it though because I know what it needs to make it work.
(Deliberately and conscientiously avoided mentioning anything to do with the words sweaty and moist)