Spare tire on bonnet aerodynamics for Land Rover Defender and Series

Back in 2011 a gentleman named CJ Burger and the Department of Mechanical and Mechatronic Engineering Stellenbosch University published a study named: 

The Effect of Vehicle-Roof Rack Configurations on the Aerodynamic Drag Coefficient

In short,  adding a spare wheel the the bonnet of a Land Rover Defender can improve aerodynamics by more than 8%, while potentially improving consume by -5%.  And this works for Land Rovers, because with Hilux it was the other way around.