You probably don’t realize how inefficient internal combustion engines are.
Range is one of the most frequent topics of discussion between electric vehicle adopters and their detractors. The usual argument is that fossil fuel vehicles can travel 700 miles between refuelings and take five minutes to do so. But the focus on range hides a very important feature of battery electric cars: they are much more efficient than internal combustion.
To illustrate this, we need to do a little math. This is made more complicated than it could be due to the different ways in which specifications for internal combustion vehicles and battery electric vehicles are stated. For the latter, you almost always know the battery capacity and rated range. For fossil fuel cars, you may not even know what your tank size is, just the rated miles per gallon. The range is usually not part of the specification. You almost certainly have no idea how much energy that equates to one kilometer.
However, when you calculate things in such a way that they are comparable, the amount of energy used by an internal combustion engine car compared to a battery electric car becomes very contrasting. This particularly came to mind when I realized that a car I owned – a classic 1992 Porsche 968 – had about the same range on a “full tank” as the car I drove it by. replaced – a Tesla Model 3 performance. Both do just over 300 miles full to empty. The Porsche could do a little more than that if it wasn’t driven like a Porsche should be, but that’s all a ‘back of the cigarette pack’ calculation, except I quit smoking it a few decades ago.
I will be using slightly different cars for this article and basing the calculations on EPA and WLTP numbers to keep things as fair as possible. The cars I chose are the Tesla Model 3 Long Range for the BEVs and the Toyota Camry to represent the Fossil Corner because it was the best selling car in America in a class similar to the Model 3 and available in worldwide, but not in the UK since November 2021. The Camry can now be bought as a hybrid, so more efficient than the combustion-only versions, but it will still make the point clearly.
Let’s start with the Tesla. The current long-range Model 3 has an 82 kWh battery, providing 374 miles of WLTP range or 358 miles according to the EPA test. This equates to 4.6 miles per kWh (WLTP) or 4.4 miles per kWh (EPA). The 2.5L Camry LE Hybrid delivers 53.3 mpg (i.e. UK gallons) according to the WLTP test and 52 mpg (US gallons) according to the EPA test. But how do you convert that to kWh for comparison?
Nobody really talks about how much energy is in a gallon of petrol (or petrol, as we call it here in the UK) in these sorts of debates. But you can track this figure quite easily. One number I found was 9.6 kWh per liter, which equates to 43.58 kWh per (UK) gallon. The usual measurement is “Gasoline Gallon Equivalent”, from which MPGe (Miles Per Gallon Gasoline Equivalent) is derived. The E10 version of the gasoline/petrol comes out at 32.78 kWh per (US) gallon, according to the United States Environmental Protection Agency.
The next thing we need to figure out for the Camry is how many kWh it takes per mile, so we need to pump those numbers into the MPG we got before. Using the WLTP MPG figure and the UK gallon energy value, you get 1.2 miles per kWh. Using the EPA MPG and gallon energy value, you get 1.59 miles per kWh. So, via the WLTP efficiency rating system, the Camry uses 3.74 times more energy than the Tesla per mile, and via the EPA rating, 3.57 times more. Where does the rest of the energy go? Waste heat, transmission friction and other inefficiencies.
Of course, that doesn’t mean that a gallon of gasoline uses a lot more kWh of electricity. It will use some during its production process, but the oil already had this energy potential when it was extracted from the ground. The point I’m trying to get across here is that an internal combustion engine uses a lot more energy per mile than a battery-powered electric motor. So much that it’s not even in the same stadium. Why are we wasting all this energy when we don’t need it?
Of course, internal combustion currently has some practical advantages – longer range vehicles, cheaper vehicles, faster to refuel. But it’s fundamentally worse technology than battery electric vehicles. It has been around for over a century and its effectiveness has improved only slightly during that time. We cannot afford to waste so much energy when an alternative is available which can provide so many extra kilometers per unit of power. This is why phasing out internal combustion for everyday transportation is so important.