## 2 Materials and Methods  
### Concept Definition and Simulation  
The objective of this analysis is to evaluate the energy efficiency patterns of a Modular Autonomous Vehicle alternative for urban mobility in an existing transport network. The primary analyzed metrics refers to the evolution of energy consumption over separate transport routes and their respective impacts on the overall efficiency of a fleet. The main results presented in this paper will highlight the benefits to energy efficiency of a modular vehicle concept while acting as a foundation for future studies regarding the overall operational costs and environmental impact of such fleets in urban areas. To identify the advantages of using Modular Autonomous Vehicles in a public transport scenario, the IPG CarMaker simulation software, developed by IPG Automotive GmbH, is used to simulate energy consumption on public routes for an autonomous bus and a modular alternative based on shuttles similar to the EasyMile EZ10 product. The CarMaker software provides support for developing and testing automobiles and light-duty vehicles, offering solutions that also fit AVs. It is an open platform that allows integration into other software solutions, such as the MATLAB R2023b environment, a graphical-based programming environment developed by MathWorks. Due to the possibility of integrating simulated models and scenarios into advanced tools such as MATLAB, the IPG CarMaker 12.0.1 choice is easily motivated for this initial analysis on the integration of MAVs into the public transport network. Further development on the following models and scenarios allows for a deeper understanding of the impact of MAVs on specific routes and can help identify the necessity or viability of such applications for each urban network in particular. With the scope of identifying the energy consumption benefits of using MAVs in a fleet, the first step implies the modeling of a full-size electric bus and a road train formed by multiple modules (individual autonomous vehicles that are interconnected). For this, a battery electric bus is modeled in another IPG solution, TruckMaker, using technical data from Solaris Bus & Coach sp. z o.o. company, Bolechowo-Osiedle, Poland. The model Urbino 12 Electric is the current battery electric bus model used by the Cluj-Napoca Municipality for public transportation. The technical specifications of this bus are presented in Table 1.  
To come across the software limitations and reduced possibility of configuration in CarMaker, the starting step of modeling implies the definition of a single module, referencing data gathered from current BEVs available in Cluj-Napoca and electric autonomous shuttle solutions existing on the market, such as EasyMile EZ10 [27]. It is considered that a driverless shuttle such as the one marketed by EasyMile, which is also already in public and private use in multiple locations and scenarios, is the most similar vehicle on the market to a module that can be used in a road train [28]. Table 2 shows the configuration defined in CarMaker for one module, considering a maximum load of 900 kg, translating to a maximum capacity of twelve passengers. For visual representation of a module's body in IPG CarMaker, a 3D model of EasyMile EZ10 is used, as pictured in Figure 2 which contains reference points. The vehicle outer shell does not have any functional impact on the simulation, being strictly used for visual representation using add-ons such as IPG Movie or MovieNX to render the digitized route, vehicle model, and its actions, as well as the behavior of suspension components and surrounding traffic and road characteristics (e.g., road profile elevations, corners or roundabouts, pedestrian crossings, traffic lights, etc.). Reference points, bodies, markers, and powertrain location are also shown in the Figure, which impact weight distribution, maneuvering, and handling of the vehicle.