Volvo has released new details about its lightweight Flybrid flywheel KERS technology, after new UK tests.

Developed together with Flybrid Automotive, part of the Torotrak Group, the lightweight Flybrid flywheel KERS technology boosts performance while cutting fuel consumption and emissions by up to 25 per cent.

The flywheel-based hybrid technology delivers an 80hp performance boost, together with fuel savings of up to 25 per cent.

The Flybrid KERS is currently testes in the S60 and fitted to the rear axle, working together with a 254hp five-cylinder T5 petrol engine.

Under braking, kinetic energy is transferred from the wheels to the KERS, and is used to spin a 6kg carbon fibre flywheel at up to 60,000 revs per minute.

When the car starts rolling again, the energy from the flywheel is transferred back to the rear wheels via a specially designed transmission. The system can either boost power or reduce load on the engine.

When the braking begins, the standard combustion engine is automatically switched off.

The system is obviously most effective in city traffic, and according to Derek Crabb, Vice President Powertrain Engineering at Volvo Car Group, it will be possible to turn off the combustion engine about half the time when driving according to the official New European Driving Cycle.”

With the KERS, the experimental Volvo S60 goes from 0-62mph in around 1.5 seconds quicker than the standard vehicle.

In addition the KERS system makes the car part-time four wheel drive vehicle, adding extra traction and stability under acceleration.

The whole system weighs just about six kilograms and has a diameter of 20 centimetres, making it very lightweight and compact.