Which of the following statements concerning ground EMS vehicles is NOT true?

The statement indicating that each ambulance must have two-inch high letters "TX" followed by the provider license number on the front and back of the ambulance is not true. Texas regulations actually require ambulances to display the license number; however, the specific requirement for the letters to be two inches in height, as phrased in the question, does not represent the accurate standard outlined in the Texas Administrative Code.

In the context of the other statements, they accurately reflect the requirements for ground Emergency Medical Services (EMS) vehicles. The emphasis on environmental systems highlights the importance of maintaining a controlled environment for patient care, especially in extreme weather conditions. Having two-way communication ensures that EMS personnel can remain in contact with medical resources, which is critical during patient transport for timely advice and support. Finally, the stipulation for all EMS vehicles to be adequately constructed and maintained ensures that they are capable of ensuring patient safety, comfort, and effective care during transport.