I've taken a look at the RUC numbers; and have come up with a few conclusions I'd like to share. Some background: The roads in NZ are maintained by using a portion of money from the "National Land Transport Fund". This Fund (NLTP) gets its money from a few different sources, including:

1. Fuel Excise Duty (FET)

2. Road User Charges (RUC)

3. Vehicle & Driver Registration & Licensing

4. Road Tolling

FET is paid by people who drive petrol cars, it is a charge they add on to the petrol price: it costs 70.024c per litre. (As a side note, the government taxes you on this FET so it actually costs 80.5276c, but this extra does not go to the NLTP so I will not count it).

RUC is paid by Diesel Vehicles (since they don't pay FET) and now also EVs.

The cost of a RUC is based on distance travelled, so you will have to buy a 1000km pre-pay card/license to display on your windshield for $76. You can buy multiple of 1000km, so if you want you can get 10,000km in one go. There will be an additional charge of $12.44 per transaction.

So, if you buy a RUC License for 10,000km, you will pay $772.44 (76*10 + 12.44). With this RUC License, if you commute 50 km per day, this will cost you $3.86 in RUC fees.

Let's compare this to a 2010 Toyota Corolla with a fuel efficiency of 7.4L/100km. This vehicle can cover 50km by using 3.7L of petrol, so by comparison the FET this vehicle will pay to travel the same distance will be only $2.59. The EV is paying ~1.5x more to the NLTP for driving the same distance.

Now imagine you have a more modern petrol car, with even greater efficiency, you will pay even less to the NLTP. Another way to look at it (if we stick to the 10,000km RUC License example) would be to think of the EV as an ICE Vehicle with an efficiency of 11.03L/100km. Because that is the efficiency of the engine you'd need to be paying the same $3.86 in FET fees.

The average age of the NZ light vehicle fleet is roughly 15 years. This means the 2010 Toyota Corolla represents the average fuel consumption of NZ vehicles,
Why then is the RUC for EVs set to equivalent to vehicles which consume 11L/100km? It makes no sense.

TLDR: EV Road User Charges are overpriced, even when you buy in bulk it's the equivalent of a petrol car with the fuel efficiency of a tank (11L/100km).
They should be priced lower to match the NZ average fuel consumption.