Commercial Driver's Licenses
If you are moving an automobile yourself, a single enclosed unit isn't going to require any type of special licensing. There will be tight turns and a little reversing involved, but hauling the trailer should not be too much of an issue.
It is obvious that a CDL may be required for an 18-wheeler, but there are some unexpected instances in which a CDL may be needed. First of all, many of the requirements are going to vary by state, but most states have a maximum gross weight of 26,000 pounds. This includes the weight of the truck, the trailer, and the cargo. However, some states require a CDL if the gross weight is over 10,000 pounds. It depends on the state laws. For example, in North Carolina, you must have a CDL for trucks over 10,000 pounds, but if the trailer and the driver originate in a state in which the requirement is 26,000 pounds, the driver is still able to freely drive through such states as North Carolina without any penalty.
The good news is that many auto transport companies use trucks that weigh above 10,000 pounds or 26,000 pounds because they transport more than one vehicle at a time, so it is common knowledge that a CDL is needed. With the 3-car hauler, it becomes difficult to stay below the 26,000 limit.
Keep in mind that your auto shipping company might require special licensing as well. You'll need certain endorsements on your CDL to transport hazardous materials, liquids, and other kinds of items. While you may not be normally hauling these things as an auto shipper, some companies haul many different items and require that all of their drivers be prepared to drive all of their trucks. Check with your company for special licensing requirements.