Torque. It’s funny how a thing so difficult to explain can be defined so emphatically with one push of a car’s ‘go’ pedal.
Suddenly it’s crystal clear. Forget the maths; more torque simply makes acceleration faster. In some cases, a lot faster.
This seems like a good time for some kind of practical demonstration. We’ll need a car, and not just any car. Leave your miles-per-gallon hat at home because, for this, we’ll need a big engine. With turbochargers. And preferably a loud exhaust for good measure.
And so, let me introduce our willing volunteer for today’s lesson: the new Audi RS 7.
Under the bonnet is, what I can only assume to be, the kind of explosion-making device that Scotland wants to ban. Audi calls it the 4.0-litre twin-turbo V8 from the RS 6 Avant. I call it a weapon of mass destruction (of super-unleaded) It’s about 20 horsepower down on the larger, normally-aspirated V10 engine in the old RS 6, but it has more peak torque and - crucially - a lot more wallop lower in the rev range.
It’s technically quite a bit more efficient, too - mustn’t forget that.
With a monumental and truly awful squeal, the stone-cold carbon ceramic anchors struggle to haul the car down to a safe speed for the corner. It turns out the optional - and huge - 420mm upgraded discs need a good bit of heat in them to work properly, making the standard steel ‘wave’ discs a better everyday bet. Fortunately, as the RS 7 and I barrel around the bend and re-deploy enough turbocharged torque to rip the tarmac to shreds, I find that there’s an almost endless reserve of grip and traction.
Audi fits all its RS models with quattro four-wheel drive, and in the 7 it gains a ‘sports differential’ at the back axle. I watched the moving display model with accompanying video three times and, to be honest, I’m still not quite sure what it does.
Because the power is split between four wheels rather than some of its rivals’ two though, the RS 7 puts around half the power down through each fat tyre and makes it almost impossible to wheelspin.
That’s a win for safety as well as granting unbelievable acceleration. Reaching 62mph from rest in 3.9 seconds is incredible for a car that - with two people, fluids and a tank of petrol on board - weighs around 2.2 tonnes.
Its top speed is electronically limited, but without the cap the RS 7 would - astonishingly - top 200mph.