In the context of ACRISS car codes, car category defines car size and level. For instance, ACRISS car categories include Mini (Hyundai i10), Compact (Renault Dokker), Premium (Audi A4) and Luxury (Audi A7 Sportback).
Each of the car category is marked with a a single capital letter. For example, Mini is marked with M, Compact with C, Premium with P, and Luxury with L.
The above-mentioned categories are just some examples. For more information on car category codes, please visit ACRISS web page.