Is "gear" necessary here? Is it common to say gear automatic/manual car?
You are absolutely correct. The word "gear" is not necessary here and most people will simply say "automatic" or "manual". I can only think that she says gear to emphasize the fact that it is an automatic car, though I do not know why. This is not a common phrase at all. Ex: I only learnt how to drive an automatic car. Ex: In the UK if you have a manual license you can drive both manual and automatic cars.
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