Most Auto Carriers prefer Not to haul vehicles with personal items due to the following reasons:

* Personal Items not part of the vehicle are not covered under cargo carrier insurance due to lack of inventory & value.
* Due to lack of insurance coverage for personal items in teh vehicle, the driver would not want to assume liability.
* In some states, transporting a vehicle packed with personal items could be a punishable offense by penalty or fine.
* On the road, there are many traffic stops by authorties & having a packed vehicle would ensure that vehicle wil get searched. 
* In the end, the driver would only assume liability based on the coverage the assigned carrier provides.

All auto carriers are required by law to have cargo insurance to cover their shipments in case of damage during delivery. The insurance that the auto carrier provides only covers the vehicle that is being transported. The full automobile and everything part of it would be covered under the Cargo Carrier Insurance provided by the driver. Items that are not part of the car would not be covered under the Cargo Carrier insurance. This means personal items such as clothes, boxes, furniture, etc...
A driver would not want to assume liability over your personal items due to lack of proper inventory. Some drivers will make an exception but that is usually a deal struck between the actual driver and the customer on site at pickup. This would usually involve a little extra kick back or what most would call a "tip". In the end, always remember that drivers are not obligated to haul your vehicle packed with personal items. Any decisions on this matter ultimatley falls on the driver who is doing the actual driving and will be held accountable for anything underthe care of the appointed carrier. 

Hope this helps. 

Of course, you can’t ship anything flammable, explosive, dangerous or illegal. 
FMCSA rules also prohibit non-vehicle-related items from being transported with the vehicle.

Rule of thumb:

Do the items “belong” in or with the car?

YES, you can include it! For example:

• Child car seats
• Car Cover
• Tools, if it’s a work-vehicle (such as a plumber’s truck)

Is it unrelated?

No, FMCSA does not allow the following:

• Luggage
• Personal items
• Household items
• Anything unrelated to the car

Why does FMCSA Prohibit Personal and Household Items?

• Excess Weight: Car transporters must enter weigh stations and are subject to other inspections along highways. For safety reasons they must limit the total weight on their trailer.
• Laws and Fines: Car transporters are not licensed by the FMCSA to carry household or personal items, and could be fined at inspection stations.
• Insurance Not Available: Because transporters are not licensed to carry household or personal items, they would be unable to obtain or provide any insurance for any non-vehicle items in case of damage or loss.

The department of transportation or D.O.T prohibits car carriers from shipping personal or household items due to weight restrictions, however, most carriers will let you put up to 100 LBS of personal items in the trunk of your vehicle while being transported.

It is an industry standard to be able to put up to 100 lbs of items in the cargo area at no additional cost.

As long as the boxed that are put in the vehicle fit that criteria, there will be no issues.

Truckers pass by weight stations in every state where they could run into hefty fines if the vehicles are over loaded.

Although car carriers are not permitted to haul household goods, we understand that sometimes it is much more convenient to put some items in your vehicle while it's being transported. Here are the things to remember: the carriers' cargo insurance does NOT cover anything inside of the vehicle. If you must put some items in your vehicle...make sure they are hidden, not sentimental or expensive, and not over 50lbs. The reason for the weight restriction is due to the fact that carriers are weighed at every USDOT weigh station and when they load their trailers they go by each cars' GVW and if they are over their limit they are shut down for 8 hours (with your vehicle) & fined.

Read more on proper vehicle transport, here.

You may have up to 100 lbs insided your vehicle. Nothing can be blocking the windows. Only your vehicle is insured. Personal property is NOT insured. 

The technical answer is that everyone quoting you are shipper/brokers who by definition do not own trucks, so it is important to know who your carrier is and what they will allow.  You see carriers that do own trucks are not licensed or insured for personal items.  

That being said: Most carriers will allow up to 100 pounds in the trunk, they typically will either charge for more weight or not accept a vehicle with over 100 pounds in the trunk. Carriers rarely allow items in the interior of your vehicle because they are not licensed for personal items and their insurance does not cover your personal items. Please note that if a thief were to break the windows to get a box or any other personal item, it will not be covered by insurance. In those cases, no one is happy and your car is damaged.