Oftentimes when shipping a vehicle customers will want to “pack” the vehicle with various personal items and household goods. This is not advisable.
When a car-carrier transports a vehicle across the country, the car-carrier must stop at weigh-stations (referred to as “the scales”) to verify that their load is safe and legal. There are a variety of problems a packed car can present at the scales. For safety reasons, the total weight of the vehicles must be lower than the gross weight rating of the trailer. If every car packed 100lbs of goods; that would be a total of 1000lbs which could put the trailer significantly over weight. In addition to the total weight of the trailer, each axle must be laden with only a certain amount of weight, and the vehicles in transport must be positioned so they “balance” over the axles. Changing the weight of one of the vehicles will create an unpredictable factor when balancing the cars.
While all of these considerations make it difficult to accommodate extra weight in vehicles, the real reason we cannot allow personal items is that it is illegal under federal law. If the officers at the scales discover personal items inside of the vehicles they can confiscate the items, fine my truck driver and even impound your vehicle. Additionally, even if YOUR car has no items in it, if another car on the carrier has personal items, it could delay the entire truck. We always try to avoid these kinds of risks.
Some companies will allow you to put personal items in the vehicle, and some companies break other laws and take other risks; you need to decide what kind of company you want to ship your car.