The publication has revealed the top five new technologies that will propel the average family car to achieve CO2 output figures of well under 90g/km and fuel efficiency levels of more than 300mpg as the European Union’s stringent regulations come into effect.

Hosted in full here, the report outlines the top five new fuel-saving technologies, comprising:

Flywheels: It’s thought flywheels – such as that being tested by Volvo – could become far more familiar on mainstream cars in the next decade because they can store waste energy and then release it, much like an electric motor and battery. Flywheel systems are also about a quarter of the cost of a hybrid set-up, far less complex and much lighter.

Variable Compression Ratio Engines: Earlier this year, it was announced that manufacturers were developing engines with variable compression ratios. Being able to vary an engine’s compression ratio depending on the demands being placed on it will lead to significant advances in efficiency.

Coasting: This will most likely be rolled out in three stages. The first stage, coasting at speed, is already a feature on some manufacturer models fitted with dual-clutch automatic gearboxes. The next version is expected to function when a car is travelling below 4mph. The ultimate version will allow transmission decoupling and engine shut-down when cruising at speed, travelling downhill or approaching traffic lights that are about to turn red.

Electric Turbochargers: Examples include the model from Audi, which uses a powerful fan in the engine’s induction system. This fan blows air through the turbo when the engine is decelerating in order to spin the turbo fan up to speed so that full boost is available as soon as the driver gets back on the accelerator. Such a system is especially useful for smaller-capacity downsized engines, which generate little exhaust gas energy, especially at low speed.

Enclosed Wheel Wells: Large steps forward in aerodynamics are difficult to achieve with mid-sized family cars. However, it is believed that wheel wells might yield big reductions in drag. The next natural step is to enclose the wheel housing so airflow doesn’t get trapped as it travels under the car.

Autocar editor-in-chief Chas Hallett said: ‘The CO2 targets laid down by the European Union are set to change the face of Europe’s car industry forever. Hitting the targets will be expensive and difficult for nearly all of Europe’s car makers and the fact that early work is already under way on cars that are still at least five years from the showroom illustrates how challenging it is.’

But Hallett said that manufacturers would need to be careful to balance the need to meet CO2 standards with costs and the risk of their models losing their consumer appeal at the expense of aero packages.

‘This is an exciting time for the car industry because the standards being set are demanding that the pace of innovation and clever technology is being maintained, if not accelerated,’ he said. ‘But car makers will have to be careful – the advance of “green” technology could prove devastating for companies already surviving on a very slim profit margin.’