For most folks, hearing “Carnot” probably means that they will be walking or using a bicycle. For some engineers, it means something entirely different. Nicolas Carnot was a French engineer and physicist who developed a successful theory on the subject of heat engines. Types of heat engines include steam, gasoline and diesel, with the later two being of the internal combustion type. Rudolf Diesel used Carnot’s writings to create his engine, which could run hotter than a steam engine. Efficiencies of heat engines are based on how much work you get out based on the energy you put in. The math involves the maximum temperature in the engine as compared to the environment. If you had an infinitely hot flame in an engine that was rejecting the heat to -459.67 degrees F (absolute zero), you could have a theoretical 100% efficient heat engine. The reality is that with available materials, gasoline engines can achieve about 30% efficiency. Less than 1/3 of your fuel’s energy goes into moving your vehicle. The rest is lost as waste heat or some may warm the car. Electric motors are a different story and are not bound by the same limitations. Efficiencies of up to 90% are achievable. For the same energy input, your car could go three times as far in the examples given. No matter how advanced an internal combustion engine is, it is zero percent efficient when stopped in traffic idling, as it is providing no work. Yes, there will be challenges to overcome as we transition to using more and more electric vehicles, but their wide spread use is inevitable. Charging a car using solar panels in a parking garage or at home will reduce our nation’s reliance on oil. For long trips maybe a hybrid would be a better choice. To those who say that it isn’t possible with all the knowledge and technology we now have is just pessimism. Our forefathers and mothers transitioned from horse drawn carriages to automobiles. They also paved dirt roads into an interstate highway system. It’s now our turn to shape a sustainable future.