Energy saving is becoming more and more important as it allows for less pollution and reduces the economic cost. To achieve energy saving we can either reduce the amount of energy used or increase the efficiency of our system. This study deals with the second option, in particular, we want to increase the efficiency of the car. We can improve it by reusing the energy from the heat of the exhaust pipe, which would otherwise be wasted. This is not a trivial task since converting thermal energy into a usable source of energy is difficult, in fact in today's cars the thermal energy from the exhaust pipe is unused.