As long as you reverse slowly, the brakes won't engage.

Especially backing down the ramp - I just put the X in neutral and let the weight of the boat/trailer pull itself into the water.

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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