White vinegar diluted 50% water,

A kitchen sponge with the scratchy feelin scouring pad with a bit of the mixture and a bit of washing up liquid.

Just did my friends subaru with it. Had nevr been cleaned inside before,

You need to identify the 'haze'. If it's accumulated road dirt, which contains all sorts of organic residue from diesel, tyre dust and brake dust, you'll need something like AutoGlym glass cleaner or some other product containing fine soft abrasive to collect the dirt for you to wipe off (liquids like Windolene or vinegar can leave marks).

If it's really obstinate dirt you may need something like rouge to get it off. If the glass itself, or a surface coating, is discoloured, you may be wasting your time and possibly make it worse.

I find a film acculmulates on the inside of windscreen and rear window ... do wonder whether it is related to air turbulance within the car, had it on lots of different cars over the years (perhaps if I only ever used the aircon and never open the windows & sunroof it would never occur?) it makes visibility a challange when the glass is wet on the outside, running the aircon does help, wiping with hand or any fabric just ends up with smears that reflect the light and worsen the situation

My solution - wet sponge using plain water only then dry using a barely damp wash leather ...