To evaluate a transport system or any other system at a system level care must be taken to consider all the aspects and stakeholders. This involves interdisciplinary approaches spanning a range of disciplines regarding engineering, economics, environmental aspects, sociology, etc. However, at the base there are fundamental aspects that need to be established first, since they impact all the system-level aspects, and quite often these fundamental aspects are not fully understood across the disciplines. This paper introduces the Mechanical Transport Efficiency Factor ( \( \Psi \) ) as a unified metric for assessing the efficiency of various modes of transport. The metric accommodates different types of vehicles, such as fixed-wing aircraft, helicopters, cars, buses, trains, and ships, by considering technology-specific figures of merit like Lift-to-Drag ratios and Weight-to-Drag ratios. The formula is further refined by incorporating the propulsive efficiency ( \( \eta _{{p}} \) ) and the payload fraction ( \( f_{\text {pay}} \) ). The paper provides concrete examples and comparative values of \( \Psi \) for each mode of transport. Our results indicate that the \( \Psi \) values allow for a more nuanced understanding of the relative efficiencies and trade-offs in a multi-modal transport network. This unified approach offers a foundational framework for optimizing and comparing emerging and existing mobility solutions.