It's unlikely the principal would wish to travel between cities by automobile. If he does, most of the security consideration in Chapter 5, Automobile Security, will apply. It's likely, however, that the principal and EP specialist will use a car at their destination. Ideally, the agent should arrange for a driver trained in defensive, security-oriented driving. Of equal importance is that the driver speak fluent English and that he know the principal's travel destinations and how to get around.
American embassies can make recommendations for good car services.
If it's necessary to use a driver who has not been trained in security, the EP specialist can still brief him, from a security standpoint, on where and how to park, how to handle the car and doors at drop-off and pickup, and the importance of locking up the car and watching it closely when it is not being driven. It is also important, when abroad, to avoid cars that clearly identify the principal as an American, particularly steering clear of overly flashy cars. From an executive protection standpoint, each method has its advantages. However, the protective measures for each differ significantly. Commercial, public aviation.