No company will allow you to ship a vehicle filled with things in it, the vehicle must be driveable so completely empty including the trunk. They will allow a small box in the trunk where you can place things like seat covers, steering wheel cover, etc... Extra speakers must be taken out as well. Gas tank must be below 1/4 fill. If you are looking at shipping things you can get a container, fill it, including a vehicle and ship it that way. Matson will allow that.
Matson does most of the shipping of cars to Hawaii. I think I ve heard that they allow you to fill up the trunk and back seat up to the windows, so that the people who drive your car on and off the ferry can avoid driving it into the ocean! You ll want to check with them to be sure.
I checked several different websites and they all say no - as the items inside the car are not insuredSorry!shipmyvehicle.com says no executiveautotransport.com says no westpointrelocation.com says no
None of them because it can be a hazard to the rest of the ship.