So following weeks of indecision I finally fitted the mudflaps to the M3. I was concerned that the attachment of the front flap to the liner would be insecure and would cause some paint rub. I now think I was worrying too much.
The rear flaps fit very securely. Really very good, it will be interesting to see if the rear camera functions better now, as all I have seen in the rain before now is spray from the rear wheels.
The front flaps have some play at the top but not much. To get some comparison I went to examine the OEM flaps on darling wife's Skoda. They are certainly not fitted any more securely than on the M3. There is plenty of plastinc rubbing against paint, but with no obvious sign of paint rubbing after 5 years. Hopefully the same will be true of the M3 paint in years to come.
The flaps generally seem to be very well designed, with drainage channels to match the drainange design on the car (like the previously mentioned draineage hole).
When fitting the passenger side front flap I drilled the pilot hole at a slight angle toward the car instead of at 90 degrees to the wheel liner. The result was a better fit. The liner is pressed firmly against the body panel where on the driver side there is a few mm gap, hence the play, perhaps there is a difference in the liners each side.
