When placed into inventory it occupies 11674.60L. And it's possible to go over the container limit (18k) by placing a second drill: total consumed volume becomes 23349.20. Though, attempt to add one more drill throws a UI message:

Max destination volume reached. Part volume is: 2637.42 (+7986.62)

Part's volume in the message looks correct.

Volume difference is actually a problem for any deployable part. Volume size on pickup differs from the one in inventory.

This bug is fixed in terms of consistency: now the volume is always calculated to the same value. Though, it's now always 11674.60, and not 2637.42 as one may expect. See #139.