Quantum mechanics plays a limited role in internal combustion engines, primarily influencing the electronic components like flash memory ICs in the Engine Control Unit (ECU). While thermodynamics often intersects with quantum mechanics, the fundamental operations of internal combustion engines are rooted in classical physics. The discussion highlights that classical theories adequately explain the stability and energy changes within engines, without needing quantum mechanics for practical applications. The heat energy changes at the atomic level can be better understood through statistical mechanics rather than quantum physics. Ultimately, the consensus is that while quantum mechanics underpins material properties, it does not significantly impact the functioning of internal combustion engines.