Short answer
The one large study that measured it found that car plants building more exterior colours used more labour per vehicle — but not in the paint shop. The cost showed up elsewhere, which the authors put down to every extra colour multiplying the colour-matched parts that must reach the line. Beyond that the explanations are interpretation: stock risk, resale, and ranges designed for many markets at once are plausible and unmeasured, and truck makers that paint in more than 600 colours show a short list is a choice, not a technical limit.
The International Motor Vehicle Programme surveyed 70 car assembly plants in 16 countries in 1989–90, covering about 60% of world assembly capacity, and analysed the 62 volume plants. Its researchers related labour hours per vehicle to several measures of product variety while allowing for plant scale, automation, the age of the design and how production was organised. Most kinds of variety, including the number of models and body styles, had little effect. Three did: the number of engine and transmission combinations, the number of wiring harnesses and the number of exterior colours, each a statistically significant predictor of more hours per vehicle in the 57 plants with complete data. The colour result was the only one of the three significant at the 1% level. Yet when the same test was run on the paint department alone, the number of colours had no significant effect on paint-shop productivity, and plant managers told the authors that variety was not a problem there.
The authors' explanation is that a colour is not only paint. Each exterior colour multiplies the small exterior and interior parts that depend on it and must be delivered to the assembly line in the right order, from stock or from suppliers just in time — body-coloured bumpers, mirror housings and trim are the obvious examples. The paint shop, by contrast, is built to switch. That reading agrees with later engineering evidence. The EU's reference document on vehicle painting notes that low-loss colour changers have made long runs of one colour less important, and gives the paint lost at a change as millilitres per sprayer. So the expense of an extra colour is better thought of as a logistics cost than a painting cost: another variant of every colour-matched component to make, store, sequence and, when a panel is damaged, match again. The study's data are more than thirty years old and predate much of today's automation.
The study also found that 'lean' plants absorbed variety with less penalty than traditional mass-production plants, so the cost of colours is not a constant: it depends on how the factory is run.
If painting many colours were simply too costly, nobody would do it. Truck and commercial-vehicle plants do: the same EU document puts their typical colour range above 600, because operators want vehicles in their own liveries. The price is real — very frequent colour changes and metres of hose to purge each time — and the industry pays it because the buyer specifies the colour, orders in volume and does not expect a matching bumper from stock. Artists' paint is another case. One maker sells its colours in nine price bands, and its staff note that an artists' paint maker depends to some extent on the demand of larger industries for the pigments it can buy. Both cases point the same way: the number of colours on offer follows who is buying and who carries the stock, more than what the factory can physically spray.
Several reasons are commonly offered for short colour lists, and none has been measured. Resale: a neutral car is said to be easier to sell on, though the largest recent US study found white and black depreciating slightly faster than average, and its publisher's analyst argues that common colours give a used car nothing to distinguish it. Fleets: a paint supplier attributed white's lead in North America in 2010 largely to fleet, light-truck and SUV buyers. Global products: a range designed once for many markets favours colours acceptable in all of them. These are explanations from people in the trade and are evidence of what the industry believes. The pages on why cars are neutral and why everyday colour became neutral set out that evidence in full; this page is concerned with the cost side.
Taken together, the measured study and the engineering evidence suggest that firms limit colours because each one adds a tail of matched parts and stock that must be carried whether or not it sells, not because paint is hard to change. That is an interpretation. One step further is a hypothesis that Colourwise has not seen tested: that the short list is driven mainly by inventory risk at the point of sale. A dealer or retailer holding stock in a colour few people choose has money tied up in something hard to shift, so the range shrinks towards colours that almost anyone will accept, and made-to-order sellers can afford more. Testing it would need what no public dataset contains — what was offered, what was stocked, what sold and how long it waited — so it stays labelled as a hypothesis.
| Reason | Kind of statement | Where it comes from | What it rests on |
|---|---|---|---|
| More exterior colours mean more labour per vehicle | Measured | Assembly-plant study, 1989–90 data | Regression across 57 plants; significant at the 1% level |
| The extra labour is not in the paint shop | Measured | Same study | No significant effect of colour count on paint-department productivity |
| Colour-matched parts multiply with each colour | Authors' interpretation | Same study | Explanation offered for the two results above |
| Changing colour wastes little paint with modern equipment | Reference values | EU reference document, 2020 | Nominal quantities per sprayer; statement on low-loss changers |
| Common colours give a used car no distinction | Industry commentary | Used-car listings analyst, 2025 | Offered alongside depreciation data; untested |
| Fleet buyers favour white | Industry commentary | Paint supplier's 2010 report | Supplier's explanation; unmeasured |
| Colours add stock and matched parts, not painting difficulty | Colourwise interpretation | This page | Reading of the rows above |
| Inventory risk at the point of sale sets the range | Colourwise hypothesis | This page | Untested; no public data on colours offered, stocked and sold |
Why: The paint shop is the part of the plant where colour count showed no measurable penalty.
Fix: Point to matched parts, sequencing and stock, and cite the study that separates the paint department from the rest.
Why: Suppliers and analysts publish reasons alongside their data, and the two get quoted together.
Fix: Say who offered the explanation and that it was not tested.
Why: The only measured evidence is from car assembly in 1989–90.
Fix: State the industry and date, and treat phones, appliances and furniture as unmeasured.
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
FactStrong evidence· 24 producers in 16 countries· 1989–1990
In a study of 62 volume car assembly plants surveyed in 1989–90, the number of exterior colours was a statistically significant predictor of higher total labour hours per vehicle (at the 1% level, in the 57 plants with complete data), alongside engine–transmission combinations and wiring harnesses.
Measured: Volume car assembly plants in the International Motor Vehicle Programme survey. Method: Regression of adjusted labour hours per vehicle on variety measures with plant controls
Caveat: An association across plants a generation ago; the size of the coefficient is on a scaled index and is not a cost per colour.
FactStrong evidence
The same study found that the number of exterior colours had no statistically significant effect on paint-department productivity, and its authors attribute the overall effect to the colour-dependent parts that each extra colour multiplies.
Caveat: The department-level analysis is reported in a footnote without its table; the parts explanation is the authors' interpretation.
FactStrong evidence
Truck and commercial-vehicle paint shops typically offer a colour range above 600 to match fleet colour schemes.
FactLimited evidence
iSeeCars' analyst attributes the weaker value retention of white and black used cars to their being so common that they offer no distinction in the used market.
Caveat: A commentator's explanation published with the data; the study does not test it.
Source: Car colour depreciation study (model-year 2022 used cars)
Colourwise interpretationLimited evidence
Firms limit colour ranges mainly because each colour adds matched parts and stock that must be carried through the supply chain, not because changing paint colour is technically difficult or wasteful.
Based on: Colourwise's reading of the assembly-plant study (colours raise total labour but not paint-shop labour), the EU reference document's account of low-loss colour changing, and the existence of 600-colour truck ranges.
Caveat: The plant data are from 1989–90 and cover cars only; no study of consumer goods or of current plants was found.
Colourwise interpretationLimited evidence
Hypothesis: short colour lists are driven mainly by inventory risk at the point of sale, so sellers who hold finished stock offer fewer colours than those who make to order.
Based on: Proposed by Colourwise from the contrast between stocked passenger cars and made-to-order fleet vehicles. No dataset of colours offered, stocked and sold was found against which to test it.
Caveat: Untested. It may be wrong, and other factors such as brand positioning are not considered.
Reviewed 1 October 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.