Vehicle Fitment Data: Comparing Defined Fitment vs Config Fitment

March 24, 2023

Vehicle fitment (or compatibility) data is one of the most critical aspects of any automotive parts business. It seems obvious, but for customers to convert and make a purchase, they need to know for sure whether that part will fit their car or not. 

All parts are designed differently and typically only fit specific makes of cars. If customers buy the wrong parts, they might not fit the car, and the customers will have to return the parts, triggering a rather lengthy process.

This is where vehicle fitment data comes in. Fitment data helps the customers look up parts that will fit their vehicle, allowing them to purchase easily. 

Within the automotive parts data industry, there are two ways to organise fitment data.

  1. Defined fitment (or definition fitment)
  2. Config fitment (or configuration fitment)

So what is the difference? 

Config Fitment

Config fitment is a style derived from OEM cataloging procedures. The method involves linking a particular part to a set or configuration of vehicle attributes which are each represented by a unique ID. For example, a part may be linked with an individual ID for a model, submodel, engine code, wheel base, body style and so on. It would be common for a part to be linked with up to 40 different individual IDs when utilising the config fitment framework. 

Config style fitment is extremely accurate as each vehicle attribute can be specifically linked and there is a comprehensive potential of attributes that can be linked. The downside with this style of fitment is that it is difficult and time-consuming to input the data, it's harder to manipulate the data as it is a fundamentally complex structure, and also often difficult for end-consumers or part buyers to interpret due to the number of variables. 

In the aftermarket parts industry, the style of config fitment has been widely popularized in the North American market by the ACES/PIES standard. Outside of this market, config style fitment is less common. 

Defined Fitment

Defined fitment is a much simpler way of linking vehicles and parts, albeit less accurate than config fitment. 

Rather than linking each part with a set of individual unique vehicle attribute IDs, defined fitment links a part with predefined vehicles. Each predefined vehicle has a set of vehicle attributes already assigned and each grouping has a unique ID. This is a far easier method for linking parts and vehicles as the concept of a ‘vehicle’  is much easier to understand and identify. The reason this method is less accurate is because predefining vehicles remove the flexibility in assigning specific vehicle attributes to a part’s fitment. 

Defined fitment is more widely adopted outside of North America as it is easier for both manufacturers and developers to understand and translate into an understandable system for buyers of auto parts. 

Each fitment style has its pros and cons. The decision is often a tradeoff between ease of use and accuracy. However, Partly gives you the option to choose which structure you want to implement in your business. Both styles of fitment can even be utilised in conjunction with one another.