I used to deliver cars and vans around the country, including brand new ones. Obviously, if I was going to drive it, say, 100 miles to the customer's home, the 'delivery mileage' would end up being far greater than the 10 miles which you quote.
However the vehicles I picked up usually already had several miles on the clock already. That's because they'd been driven from the production line to a storage area (which could be nearly a mile away), then later driven back to the main plant to have 'optional extras' (according to a customer's requirements) fitted and then driven back to the on-site storage area. They'd then be driven across the site to be loaded onto a transporter and taken to an off-site storage facility, where they'd be driven further to get to their designated bay.
Further, imported vehicles would already have undergone such moves before arriving at somewhere like Sheerness:
http://media.gettyimages.com/photos/in-this-aerial-photo-imported-cars-are-stored-at-sheerness-open-car-picture-id83146776
Simply getting from the ship to a parking bay there can add quite some distance to the odometer!