Torque vs. Horsepower: What Matters More?
What is the difference between horsepower and torque, and which is more important when shopping for your next vehicle?
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When the topic of conversation is engines, it’s all about the numbers. We can measure an engine by its displacement (in cubic inches or liters) or the number of cylinders (from three to 16), but if you care about performance, it ultimately comes down to horsepower and torque. While these numbers are commonly used in advertisements and car reviews, it’s not always clear what they actually mean.
Here, we look at the difference between horsepower vs. torque and which is—or which should be—more important to you.
What Is Torque?
Torque is a twisting force—you generate torque when you open a stubborn jar of applesauce or yank on a wrench to loosen a stuck bolt. In a car, torque is the rotational force created by an engine or motor that turns the wheels and propels the vehicle down the road.
Americans measure torque in pound-feet, which sounds awkward, but it’s worth noting this is one case where the metric unit (Newton-meters) is no more elegant. Exerting one pound of twisting force at a distance of one foot from the rotational axis is equal to one pound-foot.
More torque makes a car accelerate harder, assuming the weight stays the same. A low-weight, high-torque vehicle accelerates ferociously off the line, pushing you back into the seat like a rocket launching. Large work vehicles, such as heavy-duty diesel trucks, also have high-torque engines, but they won’t win drag races. All the torque is required to set a heavy vehicle in motion and help it carry or haul a large load.
Despite the heavy battery packs they require, electric vehicles are quick off the line because they tend to generate a lot of torque from a standstill the instant the driver mashes the accelerator. The latest Tesla Model S Plaid—the quickest vehicle on the market—can rocket from zero to 60 mph in a shade under two seconds. Tesla doesn’t release torque figures for its vehicles, but the Lucid Air Dream Edition, a main competitor for the Model S, makes 1,025 pound-feet of torque and hits 60 mph in a claimed 2.5 seconds.
A high-torque electric motor is like a light switch—flip the switch, and the light comes on immediately. An internal-combustion engine is like a gas barbecue: turn the gas on and apply a spark and the BBQ lights, sometimes quickly and sometimes not.
What Is Horsepower?
Torque doesn’t tell the full story of a vehicle’s performance, though, because it doesn’t factor in time. Consider two people who can lift 300 pounds. One struggles to lift it, grunting and periodically pausing as he heaves the barbell over his head. The other thrusts it over his head in a quick, explosive jerk. Both lifters are capable of generating the same force, but the person who moves the weight faster has produced more power.
By definition, power represents the rate at which work is done. Explained in automotive terms, horsepower is a measure of how quickly an engine delivers its torque. In the real-world, horsepower is important because it more closely relates to how quick and fast a car is—in other words, its zero-to-60-mph time and its top speed.
The term “horsepower” dates back to the late 18th century when Scottish engineer James Watt searched for a marketing hook to describe how his steam engine performed compared to draft horses. He first calculated how much weight a horse could lift over a given distance and time, then compared that figure to his engine’s performance. This standard has since become a baseline for establishing the performance of your average Toyota Corolla (139 horsepower) or Bugatti Chiron (a mighty 1,500 horsepower).
Horsepower vs. Torque: Which Is More Important?
The hypothetical battle between horsepower vs. torque is misleading. Since horsepower is calculated from torque, it’s not an either/or question. While there are exceptions, an engine that makes more torque tends to make more power when comparing similar powertrains (gas to gas, and diesel to diesel, etc.).
The other thing you need to understand is that the peak power and torque figures that manufacturers advertise are only achieved over a narrow range of engine speeds. Maximum horsepower arrives near the engine’s redline—often above 6000 rpm—so you’ll have to floor the accelerator and hold it down until the engine revs up and hits that rpm. Peak torque, however, occurs much earlier in the rev range—generally between 2000 and 6000 rpm—which means you’re more likely to experience maximum torque in normal driving than peak horsepower.
So the winner of horsepower versus torque depends on how and where you drive. If your goal is to win drag races or cross Germany as fast as possible, horsepower is everything. But the advertised horsepower number is generally only relevant when you accelerate with the pedal to the metal for several seconds. Unless you’re at a racetrack or merging onto a highway with the windows down and AC/DC blaring, that’s not how most of us drive.
A car’s peak horsepower is far less noteworthy if you’re a city dweller confined to 30-mph speed limits. In stop-and-go traffic, a vehicle that makes a lot of torque will feel punchier than one with an engine that is tuned to optimize power. Want a car that feels quick and responsive in urban and suburban driving? Look for a vehicle with a bigger torque peak occurring at a lower rpm, where most driving occurs.
