There is no general method to compare transportation efficiency. This contest entry propose using mpg multiplied by speed as definition.
Lack of transportation efficiency definition cause confusing transportation device and optimization design goal. The proposed definition is mpg multiplied by speed. The mpg (miles per gallon) part can be modified to be ton (mass) miles per gallon for cargo transport, or passenger miles per gallon for passenger transport. Transportation speed has always been important. Canal (such as Erie canal) transport was more energy efficient than railroad in the 19 th century, but potential customer choose railroad because speed in also important.
The transportation efficiency definition is applicable to land, air and ocean transport. For most people in their activities, daily land transportation consideration is readily applicable. Global land transportation efficiency contest with sponsored prize for the contest winner should be able to promote efficient land transportation technology.
There has been land vehicle maximum mpg contest with top performance of more than 10,000 mpg. These vehicles with one driver passenger are able to move at 15 mph speed on level closed loop. The winning design for this low speed vehicle is not useful in daily life. Changing the contest to useful performance level is one way to encourage useful design development. The average speed should be increased to around 40 mph. The close loop need to have some elevation change. The vehicle probably should accommodate 2 persons.