How we work
Every fault on MotorFiable comes from sources we have opened and read, and each piece of data links to its own. Here we explain which sources we use, how we rate severity and frequency, how the risk index is calculated and where costs come from.
Which sources we use
In order of preference: the higher up, the more weight a source carries.
- Manufacturers, official bodies and consumer associationsManufacturer statements, technical bulletins and campaigns; the EU Safety Gate, KBA, DGT and court rulings; organisations such as the OCU.
- Specialist pressEstablished motoring magazines and websites, Spanish and European, and reliability studies such as those by ADAC or TÜV.
- Technical documentation and spare-parts cataloguesFor part references, prices and labour times.
- Owner forumsOnly as supporting evidence. They are never the sole source of a cause, a frequency or a cost.
- We open and read every source before citing it. We do not cite links we have not consulted or addresses reconstructed from memory.
- We record the date we accessed it for each source. You will see it in the list at the bottom of each page, along with the publisher and the publication date if known.
- We write in our own words. We do not copy sentences from the sources; if a direct quotation is essential, it goes in quotation marks with its source.
- If there is no reliable source, there is no data. We prefer to write "No reliable data" or put it under "What we do not yet know" rather than give a plausible figure.
Severity, frequency and verdict
All faults are rated on the same three scales. Severity is always shown with a colour and a different shape.
Severity
| Level | What it means |
|---|---|
| Low severity | A nuisance or wear. It does not immobilise the car or damage other parts.Repair normally under €400. |
| Medium severity | It can leave you stranded or get worse if ignored, without destroying the engine.Typical repair between €400 and €1,500. |
| High severity | Risk of a serious engine, turbo or gearbox failure.Typical repair between €1,500 and €4,000. |
| Critical severity | It can destroy the engine or gearbox, or affects safety.Typical repair above €4,000 or engine replacement. |
If the cost and the consequence point to different levels, the consequence takes precedence.
Frequency
| Level | What it means |
|---|---|
| Frequency: Rare | Isolated documented cases. |
| Frequency: Occasional | A noticeable minority of vehicles. It appears repeatedly in the press or at garages. |
| Frequency: Common | Known, widespread problem in the affected versions. |
| Frequency: Very frequent | Systemic problem: the manufacturer has acknowledged it (campaign, extended warranty or design change) or it is documented in a large share of vehicles. |
For each fault we justify the frequency chosen with its sources, under "Why this rating?".
Verdict by version
| Verdict | What it means |
|---|---|
| Buy | No known serious faults, or they have already been corrected, in this version. |
| With caution | Worth buying if something specific is verified: history, a replaced part or a completed campaign. |
| Avoid | High risk of a serious fault that is hard to check for or prevent. |
Each verdict comes with its explanation, with sources, on the engine page.
Risk index
A figure from 0 to 100 that summarises an engine's documented faults. The higher it is, the greater the risk of a serious fault.
- Each fault adds points: its severity (low 1, medium 2, high 3, critical 4) multiplied by its frequency (rare 1, occasional 2, frequent 3, very frequent 4). A maximum of 16 points.
- We count only the three faults with the most points for the engine. The first counts in full, the second half and the third a quarter (weights 1; 0.5 and 0.25).
- We convert the result to a scale of 0 to 100: we divide it by the maximum possible (16 × 1.75 = 28), multiply by 100 and round.
Index = 100 × (P1 + 0,5 × P2 + 0,25 × P3) ÷ 28
This way, an engine does not score worse simply because it has more minor faults documented, and a critical, very frequent fault weighs more than several minor ones. The index summarises the risk of the known faults: it is not the probability that your particular car will break down.
If an engine's page includes a fault in the automatic gearbox it was sold with (for example, an optional CVT), we show it, but it does not count towards the engine's index: gearboxes are rated separately, on their own page or in the car's score. The clutch and the dual-mass flywheel do count.
Points for each fault
| Frequency | Low | Medium | High | Critical |
|---|---|---|---|---|
| Rare | 1 | 2 | 3 | 4 |
| Occasional | 2 | 4 | 6 | 8 |
| Common | 3 | 6 | 9 | 12 |
| Very frequent | 4 | 8 | 12 | 16 |
Risk levels
| Index | Level |
|---|---|
| 0–24 | Low risk |
| 25–49 | Moderate risk |
| 50–74 | High risk |
| 75–100 | Very high risk |
Example: the 1.2 PureTech
| Fault | Points × weight | Sum |
|---|---|---|
| Oil-bath timing belt degradationCritical (4) × very frequent (4) | 16 × 1 | 16 |
| Loss of braking assistance from vacuum pump damageCritical (4) × very frequent (4) | 16 × 0.5 | 8 |
| Excessive oil consumption from carbon on the piston rings or oil separator failureHigh (3) × very frequent (4) | 12 × 0.25 | 3 |
| Total (maximum 28) | 27 | |
100 × 27 ÷ 28 = 96. This is the index we show on the 1.2 PureTech page; its other 3 documented faults do not count towards the index, although they appear in the list.
MotorFiable score out of 10
An objective score, calculated only from documented, cited faults. There are no subjective ratings or driving tests.
Where it comes from. Each part of the car has a risk index from 0 to 100, calculated from its three most serious faults (severity × frequency, weighted 1, 0.5 and 0.25). The score is 10 − index / 10: an index of 30 equals a 7.0. So a single serious, frequent fault lowers the score even if everything else is fine, and ten minor faults do not sink a reliable car.
Scores by part of the car. Engine, gearbox, suspension, brakes, steering, tyres and wheels, electrical system, electronics and multimedia, air conditioning, bodywork and interior, and airbags and safety. The engine score is the average of the engines fitted to that car; we also show the best and the worst, because choosing the right engine changes everything. The gearbox score includes the documented automatic gearboxes (DSG, EAT, EDC…) and the gearbox and clutch faults of the car itself.
Overall score. Half comes from the engine and the other half from the rest of the car, calculated from the most serious faults across all its parts. It is not the average of the partial scores: a serious brake defect is not offset by good air conditioning.
No data, no score. A part we have not yet analysed appears as “Not analysed”, never as a 10. If a car has only had its engine analysed, its score is provisional and is marked as such. “No documented faults” means we have analysed it and found no reliable sources with known faults, not that it cannot fail.
Which cars make the rankings. Only cars with solid evidence: at least three sources on their page and five documented faults across the engine and the rest of the car. A car with few documented faults may simply be a little-studied car, not a reliable one, so its score is shown on its page with a “limited evidence” warning but does not compete in the rankings.
Scale. 7.5 or more: good reliability. 5 to 7.4: acceptable. 2.5 to 4.9: poor. Less than 2.5: very poor. Faults fixed free of charge under a recall carry less weight, because once the campaign has been carried out the defect is resolved.
Reliability of a whole car
Besides the engines, we document the faults of the rest of the car on the best-selling models.
For the cars we analyse in depth we also record the faults that do not depend on the engine: suspension, brakes, tyres and wheels, steering, gearbox and clutch, electrical system, electronics and multimedia, air conditioning, bodywork and interior, and airbags. They follow the same rules as engine faults: open, cited sources, severity and frequency on the same scales, and costs in Spain including VAT.
Whole-car index. We calculate two indexes from 0 to 100 using the same formula as for engines (the three most serious faults, weighting severity and frequency): one from the average risk of its documented engines, counting only the faults that affect the versions fitted to that car, and another from its non-engine faults. The car’s score is the average of the two; if we have not documented any of its engines, only the second counts.
Minimum evidence. We only score the rest of the car, and it only enters the rankings and comparisons, when we have found at least 2 sources and 2 documented faults outside the engine. With fewer, the lack of faults says more about what we have been able to research than about the car: we show what we have found, but its score stays provisional (engines and gearbox only) until the analysis is complete.
Recalls. A fault that the manufacturer fixes free of charge under a recall or a technical campaign counts in the car’s index with a frequency of “occasional” at most, even if its page lists it as acknowledged by the manufacturer: on a car where the campaign has been done, the defect is fixed. That is why, before buying, you should always use the VIN to check that the campaigns have been carried out.
Rankings by system. In each system (for example, suspension) we rank the analysed cars by the index of their faults in that system. A car having no documented faults in a system does not guarantee it will not fail: it means we have not found reliable sources describing it as a known problem.
Comparisons. We highlight comparisons between rivals of the same segment and era; the other combinations can be viewed, but we do not suggest them to search engines.
Repair costs
Prices in Spain, in euros, including VAT: parts and labour.
- Published figure. The range appears as-is in a source: the press, consumer associations or garages that publish their rates. On the fault page you will see it as “Published figure”.
- Estimate. Only when we can build it from cited data: the price of the part (with a source) plus the labour hours (with a source) multiplied by the average hourly rate for that type of garage. The fault page says “Estimate” and explains the calculation under “How we calculated it”.
- No basis, no figure. If there is no data for one of the two columns (independent garage or dealer), we show “No reliable data”.
- Costs are indicative: they vary with the garage, the region of Spain, the price of the part and whether the failure has damaged other parts. Always ask for a quote before repairing.
Garage hourly rate
Where these rates come from
Cifras con IVA (21 %), redondeadas al euro. Taller independiente: la IV Diagnosis de la posventa de Ganvam y GiPA (junio 2026, 725 talleres) sitúa la hora del taller mecánico independiente en 42,9 € de tarifa de tablón y 41,8 € realmente aplicada (44,9 € en talleres de red y 49 € en autocentros), sin IVA; con IVA son unos 51-59 €. Europneus (julio 2024) confirma que las cifras de este estudio no llevan IVA. El mínimo y el máximo salen de las medias por comunidad autónoma de ServiceNext (2025, sin distinguir tipo de taller): de 31,5 €/h en Extremadura a 54,91 €/h en el País Vasco, es decir, unos 38-66 € con IVA. Entre medias están La Rioja (47 €), Madrid y Cantabria (unos 45 €), Castilla y León y Castilla-La Mancha (unos 37 €) y Murcia (35 €). ServiceNext no dice si sus cifras llevan IVA; las tratamos como sin IVA porque su media nacional (41-43 €) coincide con la de GiPA. Concesionario: GiPA da de media nacional 70,9 €/h de tablón y 64 €/h aplicados, sin IVA (unos 86 y 77 € con IVA). km77 (diciembre 2024, concesionarios de Leganés, Madrid, IVA incluido) midió entre 87 y 110,7 €/h en las marcas generalistas más vendidas y 133,6 €/h en Mercedes-Benz. El mínimo es la media aplicada de GiPA con IVA y el máximo es Mercedes-Benz. Para marcas generalistas conviene usar unos 77-111 €/h. En la red oficial, los híbridos y eléctricos se cobran a más de 75 €/h sin IVA (unos 91 € con IVA). No hay datos de concesionarios por comunidad autónoma.[1][2][3][4]
Owner data
- Any owner can report a fault: engine, car, year, kilometres, cost and where it was repaired.
- We review every report before publishing it and discard those that are inconsistent or contain personal data.
- We only publish statistics for a fault when it has at least 20 approved reports. With fewer cases, an average would be misleading. Until that number is reached, the fault page shows how many reports it has and the figures from the sources.
- We show the median and the interquartile range. The median is the middle value: half of the cases fall below it and half above. The interquartile range is the interval in which the central half of the cases fall (from the 25th to the 75th percentile). That way, one extreme case does not distort the figure.
- Owners’ figures are shown separately from the sources’ figures and do not change the severity or frequency of the fault.
- We never publish personal data. Not your email or your IP address, of which we only keep an encrypted fingerprint to curb mass submissions. Privacy policy.
Corrections
If you see an incorrect or outdated figure, write to us through the corrections form. Give the page and, if you can, a source that supports it.
We check every report against the sources. If the figure was wrong, we correct it and update the page’s review date. This also applies to manufacturers, dealers and garages: the documentation they provide is reviewed like any other source.
Independence
- No manufacturer, garage, shop or partner pays to appear, to change a rating or to have a fault removed.
- Severity, frequency and the verdict are decided on the same scales for all engines.
- The affiliate links and requests to partners do not influence which faults we publish or how we rate them. How we are funded.
Sources for this page
Every fact on this page links to its source. If you find an error, let us know.
- 1.La "doble tarifa" de la mano de obra en los talleres españoles: lo que dice su tablón vs. lo que realmente ingresanInfotaller · Motoring press · published June 2026 · consulted 26 September 2026 · in spanish
- 2.El precio de mano de obra de los talleres de mecánica rápida se ha incrementado un 13% desde 2021Europneus · Motoring press · published July 2024 · consulted 26 September 2026 · in spanish
- 3.¿Cuál es el precio de la mano de obra en los talleres de las 10 marcas más vendidas en España?km77 · Motoring press · published December 2024 · consulted 26 September 2026 · in spanish
- 4.¿Estás cobrando lo justo en tu taller? Así está la mano de obra por hora en 2025Infotaller · Motoring press · published September 2025 · consulted 26 September 2026 · in spanish