OK techies, whats up with the 530 auto trans

[632 Regal]

I have read over and over that somehow BMW had implimented some software in the ECU chip that shuts the engine down between shifts so that the transition between shifts is 40 rpms. So... I suppose the 5hp-30 trans in the 540 are more durable and dont need such a close rpm alley but the whimpy a$$ 5hp-18 does, The information I find is abundant but vague at best, guess no secrets are given for obvious chip and upgrade reasons but I am still perplexed.
any ideas?

[632 Regal]

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