Torque is a measure of twisting force, usually expressed in (lb ft) pound feet or newton metres (Nm). It effectively tells you how much pulling power an engine generates; the higher the torque figure, the more easily the engine will be able to cope with heavy demands – like towing a trailer, or accelerating up a hill in a high gear.
What is torque?
It’s a rotational force that’s measured in units of force times distance. Imagine you’ve an old car that’s started with a crank handle. If the crank’s a foot long, and you hang a 10 pound weight on the end of it – about 4.5kg – then the resulting torque at the other end is 10lb ft.
Get yourself a crank handle that’s twice as long, serving as a better lever, and the torque raises to 20lb ft – meaning more force is being applied, making it easier to turn.
Do I need lots of torque?
If you like to put your foot down and get decent acceleration without having to change gear, then definitely – as engines that produces lots of torque will generally pull more readily than those with only a little.
Cars that generate lots of pulling power are generally more relaxing to drive, too, as they don’t have to be worked as hard.
Similarly, if you intend to lug around lots of equipment, or tow, then more torque is always useful. Diesel engines generally produce more torque than their petrol counterparts, and produce it lower in the rev range, making them better suited to dealing with heavy loads or off-roading.
Electric cars, however, are the kings of instant torque. Electric motors generate their maximum thrust from a standstill, which is why you’ll see the likes of the Tesla Model S giving high-end petrol sports cars a hard time from a standing start.
Can you have too much torque?
More torque’s always a good thing, particularly in heavier cars – but having a surfeit of it can lead to easily provoked wheelspin.
Consequently, a lot of cars have electronic control systems that help regulate torque and minimise the chance of you spinning the wheels.
If you’re looking at some sports, premium or off-road cars, you’ll often find that they’re fitted with a limited-slip differential (or electronically controlled differential).
These drivetrain components help spread the torque in a more controlled fashion between the driven wheels, maximising traction and minimising wheelspin.