During Monte Carlo, each team had an addition Press Car for their Press Day... See Makinen driving around in the Yaris WRC with Juha K.

In addition Citroen Racing did in fact bring 3 C3 WRCars to Monte... on of them used for guest drives with Meeke (see RedBull coverage)... I really should have gotten the License plate to see what Chasis number it was on the trusty eWRC website but I didn't...

So The teams do have additional cars lying around.. Hyundai had four in MC.

So I don't see why or how hard it could be to bring an additional C3 WRC to a home round in Corse for Breen... extra mechanics can come from Versailles... freight is easy... but for Mexico, they fly all the cars.