Thanks for all the answers including the obvious unhelpful ones
.
Looking at two of the examples of the customs duty calculation on the revenue website it seems to be either set at 0% or 12% but the examples are not car imports (I believe car imports from the US were charged at 10% with the calculatio taking the shipping costs into account), taking Zenith63’s comment above would imply that the duty rate may not yet be set for imports from the UK.
On the VAT point, if VAT has been paid in the UK already when the car was bough new, is full VAT then payable again or just the delta of what has been paid in the UK already?