Not a problem
park you car in shade.
1 - dust away windscreen,
2 - wash the windscreen with hair shampoo (any) let the screen dry.
3 - take few potatoes, peel them off slice half and slowly rub on the screen it will create some juicy spongy foam on the screen let it dry.
4 - wash again slowly with damp cloth.
if scratches are not deep you will feel the difference.
- saw this at Patel para, tested it on my EE90 it worked.