projected frontal area

[aerohead]

There is some confusion over the use of the term 'frontal area.'
The proper terminology used by all automotive aerodynamicists is 'projected frontal area.'
All automotive coefficients of aerodynamic drag are based upon a vehicles projected frontal area.
The area is taken by the shadow of the vehicle,cast upon a screen directly behind the vehicle,produced by parallel light,as sunlight.It includes all of the vehicle and has nothing at all to do with the 'front' of the vehicle.The use of this criteria is merely a convention,making all coefficients of aerodynamic drag based upon a common metric.
The shadow may coincide with the vehicles maximum cross-sectional area,but not necessarily,as with the Morelli shape,which has a unconventional side and underfloor camber.
Here's a graphic.

[Frank Lee]

"They" could include illustrations that are identical except for the vehicle facing the other way.

Or replace the term "frontal" since it causes confusion amongst laymen. "Projected Aggregate Total Cross-Sectional Area Along The Longitudinal Axis"? But that sure doesn't roll off the tongue.

[NeilBlanchard]

As someone who does a lot of drafting for a living, this is essentially what orthographic projection is - and it is called a front view. In architecture, it is called an front elevation.

If the rear wheel track is narrower than the front, then the parts of the rear wheels you can see from looking straight on - are included in the frontal area, as are the front wheels. Ditto for the side view mirrors, and the antenna sticking up on the back of the roof.