What is torque?

Any discussion of car performance is usually phrased in terms of horsepower and torque. Fundamentally, these are the two main ways an engine’s output is measured and, therefore, compared with other cars. But what is torque in a car and what does torque do?

Well, horsepower, as you can read elsewhere in this website, is a mathematically derived figure based on the amount of torque the engine makes.

And that’s the difference: Power is a calculated derivative of torque. Which means engine torque is the tangible, physical force that engines (and electric motors) really produce.

If you want the official torque definition, in scientific terms, torque is the force that wants to produce rotation. In a car’s engine, that equates to rotation of the crankshaft and, the more force – or torque - applied to the crankshaft, the more it wants to rotate.

Think about a pushbike’s pedal. When you stand on the pedal to take-off, your body weight is applying a force to the pedal and then to the crankshaft that the pedals attach to.

Because that crankshaft is a pivot, your downward force is translated to a twisting force and that’s torque. The torque then travels through the bike’s chain to the back wheel and away you go.

Car torque is no different; it simply uses pistons instead of your legs to produce that twisting force.

So, what is torque measured in? The metric unit of measurement for torque is the Newton-metre and, in the motoring world, is usually expressed as Nm. And what is Nm?

One Newton-metre is the rotational force applied by one Newton of force applied one metre from the fulcrum. (One Newton, meanwhile, is the force required to accelerate a one kilogram mass at one metre per second, per second.)

Any normal car or SUV with 500Nm or more is going to be considered pretty torquey.

A car’s torque is usually quoted as an at-the-flywheel figure. It can be measured on a dynamometer as either just the engine or as the engine as installed in the car itself.

The in-the-car figure, though, can be a bit misleading as the driveline (gearbox and differential) will usually multiply the torque meaning the flywheel number will be lower. So that needs to be taken into account when comparing outputs.

The dynamometer will also give a power figure at the same time, but what it’s really measuring is torque and then applying a mathematical formula to arrive at power.

That’s because there’s a direct relationship between a kilowatt to Newton metre torque; and the faster you can produce that torque, the more power the engine is said to have.

The rules are broadly the same for electric motors, although the torque of a motor in an EV produces its maximum torque from zero revs.

Because of the importance of torque in cars in making the vehicle actually move, EVs often feel pretty frisky when you take off. Really high torque motors can give phenomenal acceleration as a result.

The torque of a motor in an EV produces its maximum torque from zero revs.

That’s why cars with the most torque these days tend to be EVs. But large capacity turbo-diesels are also generally very torquey and produce plenty of torque Nm, too.

What is considered good torque in a car changes with technology. But realistically, any normal car or SUV with 500Nm or more is going to be considered pretty torquey.

But it’s also increasingly common to see cars with more than 600Nm torque, at which point, the thing is pretty potent.

Overall, the more torque you have at your disposal, the more relaxed and flexible the car will be to drive.

Having lots of torque means you don’t need to use the gearbox as much as the car will crank itself out of corners and from rest without a need to rev the engine hard.