The following thesis begins by analysing the Product Audit’s main activities, starting from its role in Automobili Lamborghini to the objective visual quality assessment, focusing on defects detection and classification from the customers’ point of view. Then, it moves to the Product Audit’s involvement within the qualitative improvement of vehicles, both series and pre-series ones. It analyses the importance of the activities performed before the Start Of Production. These aim at the reduction of potential defects already from the early stages of development, where corrections and modifications are faster and cheaper. It also describes the management of the corrective actions requested for series vehicles. Finally, the core of this thesis project focus on vehicle’s split lines, better known as Gap & Profile. According to an empirical study carried out by Dagman, Soderberg, and Wickman, the Visual Quality Appearance of a vehicle is also related to G&P design and their tightness; the lower the gap, the higher the perceived quality. Even though it would represent a traced aspect during the first vehicle definition done by the Marketing department, there is no standardized and objectivized Split Lines setting and evaluation process yet. The last chapter analyses the Split Lines state of art of the current production vehicles, either Lamborghini models, VW group models, or competitors ones. It starts by gathering data about G&P and inserting it into an easy-to-use catalogue. This is then used to analyse the data and providing vehicles’ evaluations according to their average gap value, representing the first step towards the objectivation of G&P. However, this method only gives a posteriori evaluation. Therefore, the next step is to define desired ranges in which gaps nominal values should be placed, helping the setting of them already from the first development phases. Finally, once the vehicle concept is released, a targeted analyses can be carried out on it. The aim is to highlight how other vehicles’ gaps are on specific split lines to justify the qualitative request, concluding with its potential gap evaluation if those requests are respected.