Which of the following statements is true regarding older vehicle models?

The statement regarding older vehicle models having only one red tail lamp is accurate. Historically, many early vehicle designs featured just a single red tail lamp, especially those manufactured before more modern regulations and safety standards came into effect. This design was quite common prior to the standardization of dual tail lamps that are now required for safety reasons.

Understanding this historical context highlights the evolution of vehicle safety regulations over time. Later models typically incorporated multiple red tail lamps to improve visibility and safety, which is now a requirement for modern vehicles.

The other options relate to regulations that apply either to newer vehicles or to conditions that do not pertain specifically to the single red tail lamp design of older models. Therefore, the distinction of having only one red tail lamp is notable and underscores the adjustment in vehicle manufacturing standards.