So working on the assumption that your TDi Disco gets, let's say 12l/100kms, your Road User Charges, add 25c to each of the 12 litres for 100kms, making the effective diesel price NZ$2.04. As the NZ/AU exchange rate is currently NZ$1.245=AU$1, your Diesel is AU$1.64.
You're right, that does sound cheap!

