What about of appliying peltier modules over car engine surface which produces electricity by working on that temprature difference of that engine?

Peltier effect AKA thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple(Peltier module).A thermoelectric device creates voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference