Conventional internal combustion engine vehicles (ICEV) generally have less than a 30% of fuel efficiency, and the most wasted energy is dissipated in the form of heat energy. The heat energy maintains the engine temperature for efficient combustion as a good aspect, but the amount of heat generation is excessive and eventually breaks the engine components unless advanced cooling system technologies are supported such as high-capacity radiators, elaborated water jackets, high-flow rate coolant pumps, etc. The excessive heat dissipation plays a key role on a poor fuel economy, but reclamation of the heat energy has not been a main focus of vehicle design. This work is first to propose a cross-layer, system-level solution to enhance thermoelectric generator (TEG) array efficiency introducing online reconfiguration of TEG modules. The proposed method is useful to any sort of TEG array to reclaim wasted heat energy because cooling and exhaust systems generally have different inlet and outlet temperatures. In this paper, we deploy the proposed method to vehicle radiator heat energy harvesting, which does not affect the vehicle performance while exhaust heat energy harvesting may disturb the combustion and emission control integrity. We introduce a novel TEG reconfiguration and maximize the TEG array output in spite of dynamic change of the coolant flow rate and temperature, which results in a huge variation in the coolant temperature distribution of inside the radiator. The proposed method enables all the TEG modules to run at or close to their maximum power points (MPP) under dynamically changing vehicle operating conditions. Experimental results show up to a 34% enhancement compared with a fixed array structure, which is a common practice.