A mechanical kinetic energy recovery system (or KERS) is smaller and lighter than a petrol-electric hybrid system, and in real-world conditions it hacks back fuel consumption by a similar percentage to a hybrid. And without troubling the engineers too much, you can add an F1-style boost function, which gives you a big lump of torque on tap if you need to overtake. Or do big, smoky burnouts. All of this, plainly, is a Good Thing.
The sort of Good Thing that’s attracted big, globo-corp manufacturers like Volvo, which has just built a KERS-equipped S60 T5 development mule, which we’ve been driving around. At the fore, there’s the company’s older 254hp five-cylinder petrol engine, powering the front wheels, and astern there’s a Flybrid KERS system powering the back axle.