The sheer bulk of data associated with hundreds of different car types, and thousands of car parts that fit in to them makes it an enormous challenge for the web developers to offer a sustainable solution that does not require manual categorisation of data.
The use of third party data tools such as TecDoc and HPI enables the retailers to identify the right car parts using API access. This reduces the time a customer has to spend on your website looking for the correct car part, and also helps the supplier reduce the time that could otherwise be wasted doing manual searches.