RUCs is the nifty little acronym for “Road User Charges” and in New Zealand, that’s what we call the tax applied to all diesel-powered vehicles.
In short, it’s a tax.
Campervans that run on diesel incur a diesel tax (or road user charge) of about $0.076 per kilometre. Campervan hire companies collect this from you at the end of your journey. If you’ve travelled 1000 the RUCs would be $76 although THL add a tiny fee of $0.05 per 100kms so you’ll actually pay $76.50
The good news is that diesel is quite a lot cheaper than petrol when you fill up the tank. Add the RUCs into the equation though and the two fuels work out about the same cost overall.
You can see all the road user charges explained here by NZTA Waka Kotahi. A Mercedes Sprinter Deuce, Venturer, or Ultima is a Type 1 and just under 3,500kg.