One crucial issue not reported in the literature is the massive amount of heat wasted by the engines of the internal combustion engine vehicles. For the first time, this research work provides a solution to recapture a portion of the mentioned waste heat. A thermally regenerative electrochemical cycle (TREC) system with the size and weight of, respectively, 50 × 30 × 38 cm³ and 3.8 kg that makes it suitable for utilizing in automobiles has been designed and built. The constructed TREC system has been embedded in a gasoline-powered internal combustion engine vehicle to harvest the waste heat of its engine. The hot cell of the TREC system has been positioned in direct contact with the vehicle's engine, and the cold cell has been located in direct contact with the lower part of behind the radiator of the vehicle, where the temperature of water flowing inside the radiator reaches its minimum value. Experimental verifications are given that explicitly demonstrate the proposed TREC system efficiently converts the waste heat into electric power and acts as an electrochemical power source with the average capacity of 0.06 kWh to charge the vehicle's battery. This means that after every 17 h, more than 1 kWh of electric energy is stored in the vehicle's battery, and in this way, 6% of the waste heat of the vehicle's engine is averagely recovered. It is also substantiated that the TREC system provides a maximum power efficiency of 7.2% in the temperature range of 35-65 °C. These results clearly prove the contribution and novelty of this research work in harvesting averagely 6% and up to 7.2% of the engine's waste heat.