– Ben Martens

EV and ICE Efficiency

Welcome to anotherĀ Tesla Tuesday! Maybe this is more of “EV Tuesday” but we’ll go with it.

Let’s talk about energy efficiency. We know that 30-40mpg is good for an ICE (internal combustion engine) vehicle. But how good is it when you consider all the available energy in the gasoline? The EPA says that a gallon of gasoline is equal to 33.7 kWh. That’s a huge amount of power but the engine only converts 25-30% of that into useful energy. The vast majority of the energy in gasoline is lost to heat.

To put that amount of energy into perspective, there’s theoretically enough energy in a gallon of gasoline to power our house (minus EV charging) for 1.5 days. When full, my F150 has almost a megawatt of power in the gas tank!

EVs on the other hand are more like 80-90% efficient. That can vary more widely though because, for example, in cold weather, heat isn’t free like it is in an ICE vehicle, so you have to use extra energy to generate heat. In an ICE vehicle you’re generating way too much heat year-round whether you want it or not.

Our Model Y LR is one of the most efficient EVs you can buy, and over the first 37,000 miles, it has averaged 278 Wh/mi (Watt hours per mile) or 3.59 miles/kWh. With the energy in one gallon of gas, it could go 121 miles.

This is exactly how the EPA generates their MPGe metric. It’s a bit of a silly calculation because you’re never going to build a car that can extract 33.7 kWh from a gallon of gasoline, but I think it is useful to understand how all those calculations work. And when you hear about how efficient a particular car is, remember that 70% of the energy it’s consuming is lost as a byproduct.