Here's a graphic for the drag breakdown measured for the Ahmed body model,researched, probably by half a dozen investigators now.
For the zero slant back configuration you can see that the entire nose drag constitutes less than 6% of overall drag,while the base drag,due to the turbulent wake is over 70% of the overall drag.This is why Hucho repeatedly emphasizes the importance of a vehicles aft-body.
We can't do anything about skin friction,so we basically ignore it.If it were an airplane we'd obsess over it.
