Most “does not fit” complaints on car accessories are decided long before the goods ship. They start when a buyer gives a factory a model name and the factory makes the part for the version of that model it knows — which may be a different generation, body style, market version or drive side from the one the buyer sells.
This guide sets out how to define fitment precisely: which vehicle variables actually change the shape of an accessory, what to send the factory, how to confirm fit on a real vehicle or from 3D data, and how to turn the result into a fitment table you can sell from. It applies whether you buy stock items the factory already makes or commission your own private-label range.
💬 Planning a range of vehicle-specific accessories? Send us your vehicle list and we will check it against what factories in Taiwan, Thailand and Malaysia already hold. Talk to us about car accessory OEM.
Why a model name is not a fitment
A model name is a marketing label that can cover several generations, body styles and market versions, so fitment has to be defined by the vehicle configuration, not by the name.
An accessory follows a panel: a window frame, a bonnet edge, a floor pan, a boot floor, a wheel arch. The panel changes when the vehicle generation changes, and it can also change within a generation — at a mid-cycle facelift, between body styles, or between versions built for different markets.
The same name can therefore sit on vehicles that share almost no body panels. A factory that says it “has” a model is telling you it holds a pattern or tool for one configuration of that model. Your job is to find out which one, and to check that it is the one your customers drive.
This is also why a factory’s model list is a starting point, not a fitment. Treat every line on it as a claim until it has been matched to a configuration you can name.
The variables that change fit
Generation, model code, body style, drive side, market version, trim and seating layout are the variables that most often change an accessory’s shape.
Not every variable matters for every product. A door visor does not care about the engine; a cargo liner cares a great deal about the seat layout. The table shows which variables to pin down for which products.
| Variable | Why it changes fit | Products most affected | How to pin it down |
|---|---|---|---|
| Generation and model year range | New generation usually means new body panels | All vehicle-specific items | Production start and end month, not just model year |
| Model code (chassis code) | Distinguishes generations and variants under one name | All vehicle-specific items | Maker’s model code from the registration document or the vehicle plate |
| Body style | Saloon, hatchback, estate, cab type and wheelbase have different panels | Visors, mud flaps, cargo liners, side steps, roof racks | State the body style and, for pick-ups, cab and bed type |
| Drive side (RHD/LHD) | Floor pan, pedal area and sometimes door shapes differ | Floor mats, seat covers, some interior trim | State right-hand drive or left-hand drive for every row |
| Market version | Versions built for different regions can differ in panels and fittings | Visors, bonnet guards, roof racks | Name the market the reference vehicle was sold in |
| Facelift | Bumper, bonnet and lamp changes mid-cycle | Bonnet guards, mud flaps, spoilers | Note “before” and “after” facelift with dates |
| Trim and factory options | Wheel-arch flares, factory roof rails, sunroof, side skirts | Mud flaps, roof racks, side steps, louvres | List the options fitted to the reference vehicle |
| Drivetrain | Floor tunnel and floor height can differ between 2WD and 4WD | Floor mats | State the drivetrain where the floor differs |
| Seating and boot layout | Third-row seats, spare-wheel position, boot floor height | Cargo liners, rear mats | State seat count and boot floor configuration |
The last two rows are the ones buyers leave out. A model name followed by “2020 onwards” does not tell a factory whether the floor tunnel is the 2WD or the 4WD shape, or whether the boot has the high or the low floor.
What to send the factory
Send the factory one written specification per vehicle configuration, with dates, drive side, body style, fitted options and photographs, so that both sides are describing the same vehicle.
A specification sheet removes most of the ambiguity before a sample is made. Use the same sheet for every factory you approach, so their answers can be compared.
| Item | What to write | Why |
|---|---|---|
| Vehicle identity | Make, model, model code, body style | Identifies the configuration, not just the name |
| Production period | Start and end month and year | Catches facelifts and running changes |
| Drive side and market | RHD or LHD; market where the vehicle is sold | Separates versions that look alike |
| Fitted options | Roof rails, flares, sunroof, seat count, boot floor | These change mounting points and shapes |
| Photographs | The panel the accessory fits, with a ruler or tape measure in frame | Lets the factory compare against its own pattern |
| Reference vehicle details | Model year and identification number of the vehicle you measured | Lets the configuration be checked later |
| Product requirements | Mounting method, material, colour, logo position | Fit depends on mounting as much as on shape |
Using the vehicle identification number
Where vehicles carry a standardised identification number, record it for each reference vehicle you measure, because it lets anyone check the configuration later.
In the United States, 49 CFR Part 565 requires every vehicle subject to the federal safety standards to carry a 17-character vehicle identification number. Positions four to eight must identify attributes of the vehicle — for passenger cars, the make, line, series, body type, engine type and restraint devices — and position ten represents the model year.
Other markets use their own identification and registration systems, so do not assume the same decoding works everywhere. The practical point is the same: keep the identifier of the actual vehicle you measured or test-fitted on, with the date, in your fitment records.
Confirming fit: a real vehicle, 3D data or both
A test fit on a real vehicle of the exact configuration you sell is the only confirmation that holds, and 3D scan data is a way to make the tool, not a substitute for that test fit.
Factories confirm fit in different ways, and each has limits.
| Method | Good for | Limits |
|---|---|---|
| Factory’s existing pattern or tool | Fast; no new tooling | Built for the configuration the factory had, which may not be yours |
| Physical template or tracing | Floor mats and cargo liners | Accuracy depends on how carefully it was taken |
| 3D scan of the vehicle | New tools for complex shapes | Only as right as the vehicle that was scanned |
| Test fit of first-off samples | Final approval | Needs a vehicle of the exact configuration in your market |
The common gap is geography. A factory test-fits on a vehicle it can reach in its own country, and that vehicle may be the other drive side or a different market version. A sample that fits perfectly in the factory’s car park can still fail on your customers’ vehicles.
For new configurations, plan for a test fit in your own market before you approve volume. If you commission a scan, agree in writing who holds the scan data and the tool design derived from it; the tooling ownership clauses cover the wording, and our guide to what drives car accessory tooling cost explains how fitment changes after the first trial are paid for.
💬 We arrange samples from factories in Taiwan, Thailand and Malaysia and can coordinate a test fit against your vehicle specification before volume. See our car accessory OEM service.
Building the fitment table
Build the fitment table with one row per vehicle configuration, and record for each row how the fit was verified and when.
The fitment table is the master record. Your listings, box labels, warehouse picking and customer service answers all come from it, so it has to be more precise than any of them.
A workable layout:
| Column | Content |
|---|---|
| SKU | Your product code; one SKU per distinct part |
| Make / model / model code | The configuration, not just the name |
| From / to | Production month and year |
| Body style | As in your specification sheet |
| Drive side | RHD or LHD |
| Includes / excludes | For example “not for vehicles with factory roof rails” |
| Verification | Tested on vehicle / factory pattern only / not yet verified |
| Verified on | Date and the reference vehicle’s identifier |
Two rules keep it honest. First, never merge rows to make a listing look shorter; if two configurations need the same part, they are still two rows with the same SKU. Second, keep the verification column visible internally, so that nobody publishes a “factory pattern only” row as if it had been tested.
Matching the table to sales channels
Marketplaces and parts catalogues describe vehicles in their own structured fields. eBay’s parts compatibility, for example, describes vehicles by year, make, model, trim and engine. In North America, the Auto Care Association’s ACES standard is the aftermarket’s data standard for exchanging product fitment data, supported by a vehicle configuration database.
If your table already holds configuration-level rows, mapping it to these fields is a translation job. If it only holds model names, every channel will force you to guess. How the table feeds into listings, barcodes and packaging is covered in our guide to packaging and listing car accessories for online marketplaces.
Keep claimed fit separate from verified fit
Mark every fitment row as verified, factory-claimed or unverified, and update it from returns data, so that the table gets more accurate with every sale.
A new range typically starts with many factory-claimed rows and a few verified ones. That is acceptable as long as you know which is which and choose where to sell first accordingly.
Feed returns back into the table. Each “does not fit” return should be logged against the row the customer bought from, with the customer’s vehicle details. A cluster of returns on one row usually points to a configuration split you did not know about — a facelift date, an option, a market version.
Do not copy a factory’s compatibility list straight onto a listing. Check it against the model codes used in your market first, as our door visor guide also warns.
Design and trademark boundaries
Use vehicle names only to describe what a part fits, and do not copy original-equipment designs or put vehicle makers’ logos on your products.
Saying that a mat fits a named vehicle is a description of compatibility. Reproducing the vehicle maker’s original part design, or printing its logo on your product, is a different matter: design rights and trademarks apply, even when a factory offers “original-style” versions. We do not arrange copies of original designs or logo-bearing parts.
As the importer you may also carry product liability for what you sell; our overview of car accessory OEM in Taiwan, Thailand and Malaysia explains how that works in Japan and the EU.
Sunsho Trade is a trading company. We do not own factories; we find, compare and manage factories in Taiwan, Thailand, Malaysia and elsewhere for each project, for stock items or for your own brand.
💬 Have a vehicle list but no fitment table yet? Send it to us and we will tell you which configurations need clarifying before you ask factories for prices. Send us your vehicle list.
For item-by-item detail, see our guides to mud flaps, bonnet guards, cargo liners, window louvres and spoilers, side steps and roof racks.
Frequently asked questions
1. Is a model year enough to define fitment?
No. Model years and production dates do not always line up, and a facelift can change panels part-way through a model year. Use production start and end months together with the model code.
2. Do right-hand-drive and left-hand-drive versions need different parts?
Often, for interior items such as floor mats and seat covers, because the floor pan and pedal area differ. Exterior items may or may not differ, so treat drive side as a separate row until a test fit shows the part is the same.
3. Can a factory work from photographs alone?
Photographs help a factory compare your vehicle with its existing pattern. They do not replace a test fit, and for a new tool the factory will usually need a template, measurements or 3D scan data.
4. Should I list “universal fit” products in the fitment table?
Keep them in the table with a clear universal flag and the dimensions that limit where they fit. Marketplaces handle universal items differently from vehicle-specific ones, and customers still need to know the size limits.
5. Who is responsible if the factory’s compatibility list is wrong?
On marketplaces the seller is usually responsible for the accuracy of the compatibility it publishes, so agree with the factory in writing how wrong fitment data will be handled. Verify on a vehicle before you rely on a factory’s claim.
Sources
Checked on 24 October 2026.
- Electronic Code of Federal Regulations, 49 CFR Part 565 (Vehicle Identification Number requirements), sections 565.13 and 565.15: https://www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-565
- eBay Seller Center, list with fitment (parts compatibility): https://www.ebay.com/sellercenter/listings/list-with-fitment
- Auto Care Association, Aftermarket Catalog Exchange Standard (ACES): https://www.autocare.org/aces