Starting with version 4.0, VirtualBox
can mount shared folders automatically, at your option. If automatic mounting is enabled for a specific shared folder, the Guest Additions will automatically mount that folder as soon as a user logs into the guest OS.
So you first have to install the guest addition in your VM.
Note:
Access to auto-mounted shared folders is only granted to the user
group vboxsf, which is created by the VirtualBox Guest Additions
installer. Hence guest users have to be member of that group to have
read/write access or to have read-only access in case the folder is
not mapped writable.
Ensure that the targeted users have been made member of the group vboxsf.
Source: https://www.virtualbox.org/manual/ch04.html#sf_mount_auto
Project /mnt/Project
. It may only be a typo then. – Takkat Mar 14 '14 at 19:36