A Guide to Auto Parts Compatibility Data for Retailers and Resellers 

May 31, 2022
A Guide to Auto Parts Compatibility Data for Retailers and Resellers 

Table of contents

I. What is auto parts compatibility?

II. The benefits of accurate auto parts compatibility data

  1. Increase auto part sales and e-commerce conversion rate
  2. Increase search engine discoverability
  3. Reduce returns and refunds on incompatible auto parts

III. Where can I find auto parts compatibility data?

  1. OEM catalogues
  2. Aftermarket catalogues
  3. Auto parts data compatibility aggregators

IV. Auto part compatibility information is always subject to change

  1. Compatibility data goes out of date quickly
  2. Sourcing
  3. Complexity

V. Things to note when working with auto parts compatibility data

  1. Data accuracy
  2. Easy-to-understand structure and formatting
  3. Integration with data suppliers

VI. How to add compatibility data to auto parts e-commerce platforms

  1. Adding compatibility data to products on eBay
  2. Adding compatibility data to products on Amazon
  3. Adding compatibility data to e-commerce product management systems

VI. How Partly makes it easy to seamlessly manage your auto parts compatibility data

  1. A centralised source of truth
  2. Partly data goes beyond the industry standard
  3. Integrated global catalogue
  4. eCommerce sales channel integrations

When looking to buy auto parts, buyers and fitters naturally search for ways to cut through the clutter and easily find and purchase the parts that suit their vehicle.

These days, online marketplaces provide a quick and convenient way to buy and sell parts online, through sophisticated back-end programmes. Ensuring that parts fit into the adopted marketplace standards can be difficult and involve significant data mapping work. Custom-built, brand-specific websites can be even more challenging to set up and manage as a vehicle data standard and catalogue need to be integrated into the website backend. 

However, integrating compatibility data into your online sales channels is essential for a successful eCommerce strategy that meets the expectations of the modern consumer.   Providing complete and accurate auto part compatibility data (also known as fitment data) to your customers allows them to buy parts with confidence. On the flip side, if the fitment winds up not being compatible with the vehicle due to inaccurate or incomplete information, there’s no end to the headaches endured for your business while managing returns, refunds, research and so forth.

While an internal process and system for managing parts compatibility is a definite step in the right direction for online sellers, it also presents a risk that leaves enormous room for ongoing business errors.

From the cost for staff to map and match parts data, the time spent maintaining and resolving errors, to the inevitable refunds and returns that occur if incompatible parts are sold.

Let’s examine why it’s so important to provide accurate compatibility data when selling auto parts online, some of the complexities involved, and why an external standard with integrated cataloguing tools can be so crucial.

We’ll also look at the steps you can take to make sure you’ve got the most up-to-date, accurate information that doesn’t lead to parts being sent back and refunded, ultimately introducing unnecessary expense and frustration into your business.

What is auto parts compatibility?

Auto parts compatibility data (or fitment data) is information about the relationship between a car and its suitable parts. It determines whether a part will fit a particular vehicle or not, based on its mechanical specifications.  
This data provides key information that lets the purchaser and the seller know which exact fitment matches their vehicle. No matter where you’re selling parts online, access to and provision of complete and accurate compatibility data is vital to your ongoing growth. 

Compatibility data is typically required if you’re selling parts online and generally comes in from a multitude of data sources, including catalogues supplied by original equipment manufacturers (OEMs), third-party aftermarket manufacturers, marketplace aggregators or independent research efforts.  

The compatibility data is generally stored in a compatibility/fitment database, a catalogue of parts and accessories corresponding to the vehicles they’re associated with.  The differences in structure and format between each catalogue can make it incredibly difficult to quickly and easily acquire and provide accurate and cohesive information when selling parts online.
Typically, the auto part compatibility data will include information such as:

  • Brand name
  • Manufacturer part number
  • Models, production ranges
  • Trims, sub-models
  • Engine codes, sizes, fuel types
  • Chassis codes, body styles
  • Interchangeable or cross-reference part numbers
  • Category or part type (fuel pump, alternator, headlight, brake pads , etc.)
  • Weight and dimensions
  • Product specification, images, and description
  • Packaging information
  • Kit content

The benefits of accurate auto parts compatibility data

There are a number of benefits associated with providing accurate parts compatibility data, especially in the competitive world of e-commerce.

Increase auto part sales and e-commerce conversion rate

By a long shot, the greatest benefit is the increased sell-rate of auto parts with accurate information. There is a simple reason for this, buyers don’t purchase a part unless they are confident it will fit their car.

The alternative to providing easily understood compatibility information is answering phone and email queries. Therefore, there’s also an enormous time saving that comes with absolving your business of the need to answer multiple enquiries over a single auto part’s compatibility. By allowing customers to order the exact part they want, your business benefits from overall customer satisfaction, and, ultimately, faster turnarounds. 

According to Partly data, adding vehicle compatibility data to a part sold online increases product conversions rates by an average of 56%. Buyers want to know they’re purchasing from a business with a reputation built on accuracy, and providing data around compatibility makes this a significant win for businesses selling parts online.

Increase search engine discoverability

Accurate compatibility data makes it easier to sell the right parts online, first time. It also gives you a favourable ranking when it comes to Google and marketplace search engines if parts and fitment information is comprehensive and accurate. So, by adding complete and accurate information to your product’s fitment data table, you provide search engine crawlers with the right data to rank your site higher and show up more in search results. 

A single auto part usually fits multiple models across various makes. As an example, a product won’t rank in search results for “Mazda 3 2011 Alternator” unless a seller include compatibility information in product description. Thorough descriptions with complete and correct fitment data enhance your chances of being found in all relevant part searches.

Reduce returns and refunds on incompatible auto parts

Returns due to inaccurate information are an issue that all online parts sellers deal with. When an incorrect fitting part is ordered, problems can start to cascade quickly.  

It is a hassle to facilitate returns and your company's reputation may suffer as a result. If a disgruntled customer needs to return an item for a refund and then needs to wait even longer, there’s a good chance you won’t attract them back.

With accurate, complete data and vehicle searches integrated into your eCommerce, you can avoid the headwinds and focus on growing sales rather than organising returns.

Where can I find auto parts compatibility data? 

The answer to this question depends on a number of different variables. Which market do you operate in, what type of parts you sell, aftermarket or OE, performance or replacement, and so on? Most manufacturers will output their parts data into either their own internal standard or a third party managed vehicle data standard.

For some brands and part types,  it’s relatively easy to find the relevant compatibility data about the parts you sell. However, it’s the matching and mapping of this data to your relevant online sales channel formats where things get complicated, quickly.  Given the different specifications that exist for different vehicle makes and models, which are multiplied out by requirements for specific regions, the task becomes exponentially more difficult to manage effectively.

As alluded to previously, there are a few main sources or formats where auto parts compatibility is usually found. There are different types of catalogues and databases, but there are a few common formats that are often used across the industry.

OEM catalogues

In general, each OEM, or OEM group, creates and manages its own catalogue, and the formatting and structure often render them incompatible with one another.  Vehicle structures are rarely represented the same way, and some part types may be named or labelled entirely differently from their competitor’s catalogues.

OEM catalogues are often developed around a specific vehicle and will include helpful assembly-level diagrams. This is particularly useful when a customer needs a replacement for a single component. However, the general structure and inconsistencies between OEM catalogues make using them highly unsuitable for any online selling or eCommerce platforms. The exception is businesses who specialise in parts for a specific make only.

Aftermarket catalogues

With many aftermarket parts manufacturers operating on a variety of different scales, most choose to not build and manage their own internal parts catalogue structure. Even if they do operate their own internal catalogue, they are often forced to map their parts data into the dominant regional standard used by their downstream distributors. 

As a result, aftermarket manufacturers frequently use third-party cataloguing technologies like Partly. These cataloguing solutions can be managed in a variety of ways. Some are built based on OEM structures and others are designed for a specific type of part and less detailed vehicle descriptions.

Auto parts data compatibility aggregators

The third type of catalogues are not created and maintained by manufacturers themselves, but rather by third parties. However, even within this category, there is great variance in the data structure, quality, types of data maintained, and even whether the data is centralised.

As a general rule, North American catalogues are configuration-fitment based while the rest of the world usually follows definition-based standards. 

Third-party aggregators are the most common data access point for resellers as manufacturers usually use these systems to map and share their data. In most markets, there are multiple different standards, resulting in manufacturers mapping their data multiple times. As a reseller, it is often required to acquire a licence to these third parts standards in order to access the data.

Auto part compatibility information is always subject to change

Given the vast range of auto parts on the market and the complexity of merging all compatibility information into a simple, unified catalogue, we can begin to appreciate the need for a laser focus on providing high-quality compatibility data.
Data collection is a continuous process and should be managed frequently. Vehicle part specifications can change as regularly as once a month! If records are not kept up to date, the list can quickly become outdated and subject to inaccuracies.

Fitment data is not always easy to handle, and it can be confusing at times. The volume of car parts, their names and derivatives can be overwhelming. Businesses selling auto parts online soon realise that they face various challenges integrating fitment data into their websites, some of which include:

Compatibility data goes out of date quickly

Compatibility data frequently becomes superseded as the vehicle industry changes.
Consider a vehicle model that has been modified to meet new safety standards or roll-over prevention criteria. In this situation, the information in all compatibility databases and on any company website that lists those exact parts for sale must be updated.
If this does not happen quickly enough, customers may check multiple sources of fitting data and discover anomalies, leading to unsatisfied customers who are likely to abandon dealing with your business.


Variations in structure, formatting and the compatibility data itself can lead to more questions being asked than answered when it comes to selling the right auto part, which obviously isn’t a good thing if you’re in business selling auto parts online.
With missing compatibility information around part compatibility or connections, part sales will ultimately be hindered, and the sales you do make could be subject to returns, refunds and the like.

Another issue with sourcing is the inconsistency of formats. A fitment database might encode its data to fit a certain platform exclusively. For example, the fitment data provided by Amazon does not fit other platforms such as eBay or Shopify.


For many car parts stores, the intricacy of information contained in fitting data poses a significant barrier. Product details such as dimensions, material, the position of the part, and the relationship between the part and the vehicle are included in fitment data. Fitment data will therefore have both static and dynamic aspects, making it extremely difficult to manage.

Things to note when working with auto parts compatibility data

Data accuracy

Accurate compatibility data is paramount when it comes to choosing an aftermarket catalogue.  Because aftermarket components are not produced by the OEM, there is generally less information for consumers to base their purchasing decision and therefore a quality user experience is needed to avoid misfits, refunds and returns. Look for an auto parts catalogue or aggregator that consistently delivers accurate fitment information.

3 important things to check when working with compatibility data

  1. The vehicle data must provide the level of detail you require for your parts.  This will depend on exactly what parts are being sold, and what the nuances in compatibility are between different makes and models.

  2. The vehicle data must be relevant and regionalised to the market you’re selling in. Working with information that isn’t relevant and regionalised to your market will create issues when buyers find their vehicle isn’t accurately represented in the data. It’s vital to your overall credibility that the compatibility data is relevant to the market you’re in.

  3. Cross-references and fitment notes are helpful for aftermarket part sellers. Armed with comprehensive and relevant information, sellers can be confidently aware of any missing details or information that’s required to ensure the highest level of accuracy.

Easy-to-understand structure and formatting

By having access to data in an easy-to-understand and universal format, you increase the chances of making it easy for customers to make the right choice in choosing to buy from you.  With a clear and precise data structure, sellers enjoy the benefits of being able to sell products globally, allowing them to scale, minus the cost increases associated with customised, manually managed structures.

Integration with data suppliers

Rich, cohesive and consistent parts data also supports a digital infrastructure for downstream data sharing, by accessing data shared from the wholesaler or manufacturer.  With more and more multi-channel e-commerce businesses emerging, having access to accurate information in real time is crucial to successfully selling the auto part.

How to add compatibility data to auto parts e-commerce platforms

The level of complexity that is so inherent to the fitment market means that there is rarely a clear and singular way to approach adding compatibility data to online platforms. The reality is that each marketplace often utilises different standards depending on where they are in the world.  In short, it really depends on the sales platform.

With standards for auto parts in Europe being markedly different from those in, for example, the United States, it’s not always a case of ‘if the shoe fits’ when it comes to auto part fitments.

Adding compatibility data to products on eBay

Ebay is one of the most prominent global online marketplaces for auto part sales and is open to auto parts retailers operating at varying degrees of scale.  There are a number of ways that you can manage your eBay listings, including the ability to manually upload compatibility data for each individual product, or by using a third party API software like Partly.

Once again, compatibility in each market is different and therefore the Master Vehicle list utilised by eBay is unique to each region. This means that the tools available to assist with this process are also region-dependent. 

Adding compatibility data is well worth the investment, with sellers reporting average conversion rate increases of above 40%. For smaller sellers, or for sellers with frequently changing one-off sales, it may be easiest to simply utilise eBay’s in-built tools to add compatibility based on your own internal or researched knowledge. However, if you deal with a large inventory of parts across multiple brands, manually adding fitment becomes near impossible. 

This is where a tool like PartsPal becomes valuable as much of this process becomes automated. Using a tool like this leverages manufacturer catalogues and allows you to bulk match fitment to your parts.

Adding parts compatibility to eBay listing can increase sales conversion by 40%

Adding compatibility data to products on Amazon

Amazon’s auto parts marketplace is generally only available to authorised brand resellers or well-established, highly-reputable retailers.  
Entering compatibility data to Amazon Automotive requires integration as a fitment data provider, which uses their Seller Central as a pipeline for transferring the relevant data into the platform. 

To provide fitment data as a seller, you'll need a separate Seller Central account from your main account. You can also provide fitment data to Amazon indirectly via a third-party compatibility data source.

For listings in the United States, for example, compatibility data is submitted in the ACES format via .xml feeds, passing through several checks and balances, the last of which matches compatibility data to Amazon’s catalogue.  However, be aware that different standards are required in markets outside of the United States.

Adding compatibility data to e-commerce product management systems

If you’re manually uploading your product and compatibility data to an e-commerce platform like Shopify, BigCommerce, or WordPress, you will need to integrate your own vehicle search and fitment filtering systems.
Because the majority of e-commerce platforms support simple product structures and are category-agnostic, most are ill-equipped to support compatibility data’s level of sophistication without a third party application. 

Unlike marketplaces like eBay or Amazon, there is no master vehicle list to map the compatibility data.  E-commerce platforms will support a number of product qualifiers, however, there is no straightforward solution when it comes to aligning that data to your product listings.

Again, by using a software integration like Partly, you save on time and hassle while removing room for error.  Information only needs to be updated once, with the new information being pushed through each of your sales channels, almost instantly. In addition, frontend vehicle-part compatibility systems become easy to integrate.

How Partly makes it easy to seamlessly manage your auto parts compatibility data

Partly is a professional catalogue management platform used by companies throughout the auto parts supply chain to map, manage and utilise auto parts data online. Partly allows you to manage compatibility from one centralised location, and easily push your parts and updates to all your ecommerce sales channels, or wherever you need them via an enterprise API.

A centralised source of truth

Partly makes it easy to navigate the constant changes and updates to auto parts products and compatibility data through PartsPal.  By housing all of your information in one place, you only need to enter it once, while Partly takes care of delivering the information and updating your sales channels with the click of a button.

Auto parts catalogue management software PartsPal

Partly data goes beyond the industry standard

Our information takes the established structure and formatting of the major catalogues and streamlines it into a format that is accepted across all major marketplaces and sales platforms, standardising the information so that it’s readily understood by potential customers.

Integrated global catalogue

By aligning the Partly platform to standardised global auto parts catalogues, Partly is designed to ensure that you’re able to quickly and efficiently list and update your product information with confidence, providing accurate information based on the Partly global data catalogue, complete with easy compatibility and OEM part links to cross-check your inputs.

eCommerce sales channel integrations

Partly is a flexible platform with out-of-the-box integrations that allow you to easily manage your product inventory and associated compatibility data, whether you’re selling in the global marketplace or locally. By giving you the confidence that you’re providing the best, most accurate information, Partly gives you the ability to scale your business with a reputation of first-time accuracy and dependability.

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