Ok for Ypres guys drives S2000 or R5. But look at belgian championship : how many top guys do it ? Not a lot ... And GT cars started in the back of the field last years And the guys who have BMW doesn't the rally at all ... the guys we find on entry list are more or less these who have ERC homologated cars.
And it's for sure easier to rent a S2000 in Ypres than in Ireland. You have more travel cost to go in Ireland, and the first is simply to take the boat, whereas in Belgium you can find closer S2000 to rent.