I imported a campervan from Germany this summer.
Key point is the weight:
Over 3.0 tonnes unladen VRT = €50 appprox
Under 3.0 tonnes unladen VRT = 13.3% of OMV (open market value in Ireland)
A camper over 3.0 tonnes is a pretty big camper... I imported a 1989 model and was charged €1863 initially, reduced by €500 on appeal.