Owners of diesel-fuelled vehicles however, must pay their RUCs separately, at a variable rate of about $60 per 1000km.
These charges cannot be paid at the local service station when buying the diesel. Oh no, nothing quite so simple.
Compliance requires trips to distant PostShops, form filling, lump sum purchase of a minimum 1000km at a time and windscreen display tickets to prove it.
It's a maddeningly cumbersome, complex, technologically ancient payment format reminiscent of Stalinist bureaucracy.
Aside from the considerable inconvenience, the main problem for low income diesel vehicle owners is finding otherwise uncommitted lump sums of $60 in order to remain street legal. And, of course, if $60 is hard to find, two, three, four times that and more becomes impossible. Before you can say Bay of Islands, arrears mount to colossal levels.
It would be so much easier if a way could be found to pay it at the pump, or in far smaller increments, but apparently this is beyond the NZ Transport Authority.
The discrepancy between the taxation regimes applied to the two fuels is a historical anomaly that has arisen because while most petrol is used on the road, much diesel is used off-road on farms and at sea where road user charges do not apply.
So farmers, boaties and shipping magnates can remain untroubled by inappropriate charges, the rest of we humble diesel vehicle owners live in constant fear of incurring arrears to which fines can be added (just to make the whole process even more difficult considering finding lump sums, rather than recalcitrant unwillingness to pay, is the main problem in the first place).
This time I had to buy a bank cheque and a stamp and envelope to pay the arrears by snail mail because once NZTA discovers the stately old ute's RUC arrears during the six-monthly warrant check and sends an account, it forbids payment at the PostShop, making the whole business doubly difficult. I kid you not.
I was thinking of writing politely to NZTA to suggest my brilliant idea for resolving this unsatisfactory, ongoing, antediluvian shambles but decided to go public because my last letter was clearly wasted on the desert air.
It's called Diesel Card. Linked electronically to registration numbers of eligible vehicles, it's issued to registered diesel owners who keep it charged regularly with money.
When we buy our paltry $10 worth of diesel (say) at the pump every week, we use the card which automatically deducts the correct percentage of RUCs at the same time. Magic.
Hey presto, no form filling, queuing or big fat unpayable bills accumulating menacingly in the depths of the filing system ready to gobble up any passing treats on the horizon.
