## 2 Materials and Methods  
The study evaluates the throughput performance of various routing protocols in Vehicular Ad Hoc Networks (VANETs) under city and highway scenarios. The protocols analyzed include AODV, AODV: TOM, AODV:DEM, GPSR, GPSR:TOM, and GPSR:DEM. Simulations were conducted using different network parameters, such as traffic generation rates, packet sizes, mobility speeds, and pause times, to reflect real-world Smart  
Figure 1: Vehicle interconnection architecture. City environments. The throughput was measured across these scenarios to assess the performance improvement provided by TOM and DEM profiles compared to baseline protocols. Statistical comparisons were made to determine the best-performing protocol for reliable data transmission in complex vehicular networks. The throughput was optimized via two optimization methods: the Taguchi Optimization Method (TOM) and the Differential Evolution Method (DEM), as shown in the flowchart of Figure 2. The process started with optimizing the routing protocols parameters for a specified scenario and performance metric. This process is achieved with two optimization methods, a single-objective optimization (TOM) followed by a multi-objective optimization (DEM) process, to find the optimum solution of the fine-tuned parameters values, as shown in our previous publication [1]. The goal of the TOM is to identify the best fine-tuned values for a set of routing parameters in each routing protocol that optimizes one of the network performance metrics (throughput). Further, the optimum solution obtained by TOM is used as initial conditions for the DEM to find a single solution for all network performance metrics. The optimization process results in a set of parameters that are fine-tuned values of a routing protocol in each VANET scenario. Further, the optimization results are used to design and implement CM-AODV and CM-GPSR routing protocols. Chameleon Method Routing (CM-routing) mechanism is inspired by biological nature of the chameleon lizard. Chameleon lizards tend to change their skin color to the surrounding environment to either hide themselves from being hunted, or for hunting. Similarly, CM-routing aims at fine-tuning the routing parameters of routing protocols, which results in the highest network performances for a running network situation. This stage emphasizes the design of the CM method and its integration with two routing protocols (AODV and GPSR). The Chameleon method is aimed at obtaining the best performance of a routing protocol when a network device moves from one network scenario to another. Figure 3 shows the flowchart of the CM. CM assumes that a best solution is given for each VANET scenario, which is obtained by the optimization mechanism. Further, the obtained optimum solutions are integrated with the routing protocol as profiles mapped to the desired VANET scenario, then a routing protocol selects the best profile for the current running situation. There are two vehicle connection routing protocols: (1) AODV as topological routing and (2) GPSR for geographical routing. Both protocols are selected to integrate the CM for their merits and features [16]. AODV is a topology-based routing, and its use for VANETs has been shown from the literature; its performance has been widely studied, but no literature reported rigorous optimization [21]. AODV is a topology-based protocol and reactive routing protocol; it requires no periodic dissemination of information like proactive protocols, which reduces the protocol overhead. Further, the reactive nature of AODV implies its quick response to changes in VANET topology [22]. AODV uses destination sequence numbers to ensure a loop-free path and make it more suitable to frequent topology changes, as in VANETs.