- Try not to wash in direct sunlight (maybe try evening)
- Try to wash and dry sections of the car instead of the whole car, see if this works
- If you have ONR, add a bit to your car soap solution. Someone told me it softens the water
- Try rinseless wash
- Get a water softener system (forgot what its called but its pricey)
- Use CarPro Spotless
That's all I can come up with