Long time ago, horsepower bragging rights came in cubic inches. American car ads in the '70s screamed "Dodge Charger with 426 Hemi" while European engineers measured the same thing in cubic centimeters. Then, somewhere between import trading regulations and the oil crisis, the world decided that liters just made more sense.
A liter is a unit of measurement for volume used to measure liquid or fluids like gasoline or oil. In engine-speak, liters represent the total cylinder displacement, which is the volume of air-fuel mixture an engine can draw in during one complete cycle. One liter equals 1,000 cubic centimeters, so your 2.0-liter four-cylinder engine goes through roughly 500 cc of fuel per cylinder, give or take a rounding error.
In the late 18th century, the metric system was born in France and slowly spread across Europe. The U.S., however, clung to the imperial system (which uses quarts instead of liters) well into the 20th century. This metric shift became practical for numerous industries — including automakers — which caused them to lean into liters for international consistency. Even the U.S. joined the club in the late 1980s through the Omnibus Trade and Competitiveness Act of 1988, agreeing to use the metric system in weights and measures for trade and commerce. Since then, displacement in liters became more than just a spec; it was an identity. A 3.0L V6 sounded smooth and powerful, while a 1.3L turbo whispered fuel efficiency. Liters became the lingua franca of performance, precision, and practicality all rolled into one neat decimal point.
Here's the thing: Engine liters still matter, even amidst the rise of technology. A bigger engine usually means more displacement –- more air, more fuel, more power. But thanks to turbocharging and electronic fuel injection (EFI), that old rule of thumb is starting to look a little outdated. A modern 1.5-liter turbo three-cylinder can outgun some 2.4-liter engines from two decades ago, all while sipping less fuel and making fewer emissions.
Still, displacement remains useful shorthand for vehicle classification and taxation. Many countries like France, the United Kingdom and Japan tax cars by engine size, not horsepower. A 1.6L Mini Cooper Coupe might fall into a friendlier tax bracket than a 2.5L sedan even if the latter is only marginally quicker. And in the age of electric motors, "engine size" is becoming a kind of automotive ghost story. It doesn't mean they will gone immediately, but with the advent of EVs, the days of liters are dwindling down. There's no displacement in an EV — just kilowatts and torque curves that start at zero RPM. Someday, we'll be bragging about car specs like "My Tesla Model S has over 1,000 horsepower. Bet?"
Don't worry, liters will still be with us for a period of time. Give it a decade or so, and we'll be telling kids how our cars used to breathe and run through cylinders while measuring their capacity in liters.