The car wash brushes are your main problem. Regardless of the material used they are still exposed to people who use them to clean the wheel wells and engine bay etc and they pick up tons of debris. When I go to the local do it yourself car wash I always bring my own microfiber wash sponge.

Beyond that, if you're touching the car with anything other than a stream of water, use very clean microfiber towels, lubricated with a soap or liquid detailer.

NEVER wipe the car in a circular pattern. On horizontal surfaces, such as the hood, roof and trunk, move the microfiber in a linear fashion, front to back. For vertical surfaces such as the doors and tailgate, use an up and down linear motion.

This will still leave very minor scratches (unavoidable in any scenario) but at least they won't reflect the sunlight as obviously to the eye.

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12 X5 M - 06 X5 4.8iS - 03 X5 4.4i - 03 M5 - 02 X5 4.6is - 99 M3 Dinan S3 - 98 M3 - 92 850i-6 - 92 850i - 91 325ix - 89 M3 2.5 - and a few parts cars