My wife bought this fancy glass cleaning cloth a year or so ago.
Some sort of microfibre thing.
She uses it for windows,mirrors,TV screens etc.etc.
Just make it damp and off you go (the cloth,not the wife...)
Totally smear free,so I thought 'sod it' and gave it a go on my car windows.
It's bleedin brilliant outside and in.
I wish I could remember what it's called...