Aerodynamic performance of passenger vehicles is one of the most efficient methods to further reduce the CO2 emissions and comply with the increasing constraints in the legislation. Previously performed studies on exterior warning accessories (systems with visual alerting signals that may be found on intervention vehicles e.g. ambulances), indicate a significant degradation of aerodynamic coefficient (Cd). Even if this category of vehicles does not have to comply with the standard emission rules, it is important to study and discover the means to reduce aerodynamic drag for this type of vehicles considering the general aim to reduce air pollution. The target would be to have a Cd level equal to that found in the base vehicles, before transformation (i.e. often, intervention vehicles are obtained by converting a vehicle available to general customers - multistage vehicle transformation).The current paper’s purpose is to continue the investigation on methods to improve the aerodynamic performance of intervention vehicles. This will be done by compensating the shape and dimensions of the warning devices with the addition of supplementary body elements or by adapting existing parts. The Cd value of the different configurations is assessed using computational fluid dynamics (CFD) software based on Lattice Boltzmann mathematical model. 3D models of different generic body type vehicles (sedan, hatch back, SUV) were created and immersed in a virtual wind tunnel. To simulate the real-world measurement method specific boundary conditions on walls, inlets, outlets were set while the fluid environment was defined with a network from fine (2mm length, near the studied model), to coarse (20mm length, near exterior walls).The results indicate that there is great potential in reducing the aerodynamic drag and, by extension, fuel consumption and CO2 emissions for all body types studied. Deviations could exist due to different make designs, or diversity of warning devices for example so the results obtained have a general nature. Nevertheless, the conclusion remains the same: if one’s aim is to improve air quality or prepare for new legislation (that will also apply to intervention vehicles), the aerodynamic optimization should be further scrutinized as it can prove to be a robust method to obtain the targeted results.