Methodology and sources
Every number here has to earn its place. This is the rulebook for how a figure gets on the page, and when we leave the box empty instead.
Source ranking: which source takes priority when two disagree
A fixed pecking order: rank 1 is the most authoritative source, rank 4 the least. When two sources disagree, the highest rank on hand wins; the lower ones only fill in around it, and we label them when they do.
| Source rank | Source | Use |
|---|---|---|
| 1 · register/official | RDW open data (NL), KBA (DE), comparable registers, type-approval data | Leading for type-approval data, recall notices and manufacturer service bulletins |
| 2 · manufacturer datasheet | Official factory datasheets and technical brochures | Leading for version specs (power, WLTP, dimensions, payload) |
| 3 · curated reference | Recognised technical reference works, trade press with method | Only to confirm tier 1/2 or bridge a gap, labelled |
| 4 · owner sources | Owner forums, aggregated public owner figures | Never as a spec; only practice indications, with the report count |
An owner figure never overrides a register or factory specification. Where tier 1 and tier 2 differ (e.g. WLTP vs type-approval), the factory figure shows and the deviation is named, not averaged.
Rating categories: source and weighting
Each category score is a number from 0 to 100; higher is better. There is no total or composite score — the categories stand on their own. Six categories. Per model the source used and the reference date are visible at each category; that field is mandatory in our data. A category gets a figure only with enough traceable data points; otherwise the score stays empty and the page shows "insufficient data". WLTP refers to the official EU lab test for fuel use and range. The last column shows which source counts most heavily toward the score and which is only supporting.
| Category | Based on | How the sources are weighted |
|---|---|---|
| Sustainability | WLTP consumption/emission, battery and drivetrain warranty, public life-cycle (LCA) indications, e.g. from the ICCT (International Council on Clean Transportation) | Factory figure weighs heaviest; LCA only with an independent source, otherwise not weighed |
| Reliability | ADAC breakdown statistics (segment/model where available), recall and technical-service-bulletin (TSB) data from official vehicle registers (RDW in the Netherlands, KBA in Germany), aggregated owner signals | Register and breakdown data lead; owner signals confirm direction, never sole basis |
| Efficiency | WLTP as reference | Relative within segment/drivetrain; no euros, no cost price |
| Combined consumption | WLTP combined plus owner real-world (shown separately) | WLTP and real-world side by side, never merged; real-world only with enough owner reports |
| Practicality | Dimensions, boot, payload, towing weight from manufacturer datasheet or official register | Published measurements only; no subjective driving feel |
| Value retention | Residual-value indications from public, methodically described sources | Only with sufficient reliable points; with thin data no figure |
Efficiency is relative within segment and drivetrain. Browse models in the catalogue.
When the box stays empty
When a figure is missing here, that is usually deliberate. The reasons vary: too few traceable points, a source so broad it tells you nothing useful, or two sources that flatly contradict each other and we cannot say which is right. In those cases the page reads "insufficient data" and we leave it there. We do not interpolate, and we will not borrow a number from a neighbouring model to fill the gap. If you cannot trace a score back to where it came from, it has no business being on the page.
Reference-date discipline
Specs, prices, ratings and tax references carry a reference date. If the underlying source changes (new model-year datasheet, new statistics, a price change), the reference date moves at the next revision, so we never leave an old value sitting on the page dressed up as current. Tax references are always indicative and tied to the stated reference date rather than to "now".
Prices and price history
Prices are indicative "from" prices with a reference date, not a quote and not a current daily price. Currently-orderable models show a from-new price; discontinued models show no new price, at most a historical introduction price as context. The price history (/en/auto/…/prices/) is a series of recorded from-prices, each with its own date, kept up by hand from official price lists. It is not a live quote feed, and we never close it off with a "model A is cheaper than B" conclusion.
Real-world consumption
Besides WLTP, some models show owner-reported real-world consumption. It sits next to the factory figure rather than replacing it, as a separate value with its unit, source, sample size (n -- the number of owner reports) and reference date attached. If the sample is too small or we cannot trace it, the model simply shows no real-world figure. We do not run our own measurements; what we do is label where each number came from.
Reviews as input
Summaries of external sources are labelled, summarised transformatively and linked to source. Owner reviews come in anonymously, are moderated before publication and smoothed only on spelling and readability, never sentiment or figure. An individual review is never on its own a rating source; only aggregated, traceable signals weigh in. See the review policy and the transparency page.
How to report a wrong figure
Misleading or incorrect product information is a real liability risk; traceability is our structural mitigation. (This is also our safeguard under Dutch law on misleading information, art. 6:194 BW.) Think a spec, price or score is wrong? Report it with a source through the contact address. We test the report against the highest available source tier. Safety-critical fields (towing weight, payload, braking distance, recall status) get priority and a visible reference-date adjustment where relevant. If the report does not hold against a higher source, the value stays and we explain on request.
No tax or financial advice. Every figure shows its source and reference date. Always compare with an independent adviser and the official source.
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