Yes, same as wings!
In reality things are more complicate: car-body-downforce depends much of the distance to the track.
The AX2 car has such a system, you can see the diffusor.
But defined is a wing-front, that doesn´t exist. The wing-rear is correct. A complete drag definition could include the car-body-effect:
What would be more realistic is to have a set of multiple [wing-part] declarations.
For a car with a front wing, a rear wing and a body shape that acts as a wing you could have three declarations:
[wing-front]
[wing-body]
[wing-rear]
This could be useful for other cars that have more than the normal front and rear wings as well... Don't even suggest modelling the interference of flows with turbulence...