there is no penalty for new buyer ... if he's not catched by Garda or customs on the road ,driving it for over limited-legal time . main thing is to get hand written letter with sell date .nobody does any investigations if U get to VRT office yourself ,not forced by custom or their records .
I know , if customs stops u with UK reg , and they can prove that u have it for a while and it was on the road , u either pay fine on the top of VRT , or must get the car out of the country ,and everything must be done in 10 days time or so . and u CANT sell it here in Ireland to other buyer ,as now its yours responsibility to pay vat or get rid of it out of country, cant resell it here.they will have your details ,and u will be in trouble .