Audi Rs3

Lol Audi have no idea how much the VRT will be. What year is the RS3?

Never mind that, how do you trade in a vehicle in NI? What dealer would want to do that?

But that trade-in is an import to Ni. Would they be bothered with the paperwork?

They've imported a car from Ireland. How does that not require paperwork?

Here you go @bewhiched :

VRT Calculator

It doesn't matter what price you purchaser the car at, it is what Revenue think it is worth that comes into play for VRT.

As mentioned before, Audi won't know or even care about the VRT.