Listen to This Post
When used in reference to shipping road vehicles, intermodal auto transport is defined as the using or changing more than one mode of transport to take a vehicle from one location to another. This can be one or more carriers or vessels. The word can be broken down by the terms "inter" which means between and "modal" which in this context means mode (or method of).
Therefore, it literally means between modes of transportation. In auto shipping it refers to using more than one shipping method to get a vehicle to a destination.
Intermodal transport of a vehicle is typically encountered shipping a car overseas. So, for example if you are sending a vehicle to Puerto Rico from the USA, a car carrier will pick it up from the location (such as a private residence, business, dealer, auction, etc.) and it will arrive at a port. The port will then load it on a container ship or it will be rolled on and off. This is otherwise known as roro shipping.
In nearly all cases where the vehicle is shipped state to state, Intermodal methods of car shipping are not used. This is because the same carrier takes and delivers the vehicle from its point of origin to its arrival location. An exception to this would be when a car carrier breaks down and another comes to collect the vehicles to finish transfer. Other times like in tight cities like Manhattan or Boston, the carrier may have a local flatbed service take the vehicle to your location in order to provide door to door transport.
There are a few examples of this type of shipping you can apply to get a better idea of what this is.
A vehicle is traveling from the east coast to Hawaii. This vehicle will get picked up on a open carrier and travel over 2000 miles on this truck to the Long Beach or Oakland port. The carrier is one mode of transport. The ship on the other end of the country is the second mode, taking it to Hawaii.
A vehicle traveling from Florida to Puerto Rico. In this case a local carrier will come to get the vehicle. Even though it may only be traveling 100+ miles, it's still being sent on a small carrier to the port for door to port service. Therefore, it still intermodal because it's using more than one mode of transportation.