What we measure
We record the asking price, kilometres, build year and version of used cars advertised for sale in New Zealand, from dealers large and small. The same car advertised in more than one place is counted once. Listings are checked twice a day, so a car’s price history builds up day by day.
Every price on the site is an asking price unless it is marked as sold. Asking prices are what sellers hope to get, usually a little above what cars change hands for, so they are a guide to the market, not a valuation of a particular car.
Medians and the typical range
Prices are medians: half the cars are advertised for less and half for more. A median isn’t pulled about by one unusually cheap or expensive car the way an average is. Prices on pages are rounded, and counts are given as “about”.
The typical range is the middle half of the cars: from the price a quarter of the cars are below to the price a quarter are above. It is shown only when a group has ten or more cars, so its ends are never one car’s price.
Minimum numbers
We never show a figure for fewer than three cars, and we never show an individual listing. A model with fewer than three cars for sale has a page but no figures, and it is kept out of search results.
A build-year page (such as a particular year of a model) is listed in search results only when twelve or more cars of that year are for sale.
Cars with under 1,000 km (usually ex-demo or delivery-kilometre cars sold at near-new prices) are left out of used-car figures and shown as their own group.
A price move over time is stated only once we have at least 8 weeks of figures for a model. How long cars that left the market had been listed looks back 90 days.
When figures update
Listings are collected twice a day. Whenever new data arrives, the figures for every model are worked out again and the pages switch to the new set together. Each page says when its figures were worked out.
The price index
The average asking price moves when the mix of cars for sale moves. Our weekly price index compares like with like instead, and changes are shown only once eight weeks of the index exist. How it is worked out is explained on its page.
Official figures and credits
Counts of cars on the road and newly registered come from the Motor Vehicle Register of Waka Kotahi NZ Transport Agency, published under a Creative Commons Attribution licence. They count cars, never prices. The figures are credited on the pages that show them, and they are checked for new months each week.
What we leave out
We never show single listings, the cheapest or dearest car in a group, or the names of the sites we collect from. Groups too small to show are left out rather than guessed at.
Questions or corrections: use our contact page.