Designed at Ford's technical centres in Dunton, Britain, and Merkenich, Germany, the engine was built at the marque's plants in Craiova, Romania and Cologne, Germany.

'Small enough to fit on a sheet of A4 paper', the engine uses a low-inertia turbocharger to deliver power quickly when the throttle is opened from low revs, the marque says.

Ford's fuel efficiency innovations include a new exhaust manifold cast into the cylinder head, a unique cast iron block that warms the engine more quickly than a conventional aluminium block 'to cut the amount of 'warm-up' energy required by 50 per cent', and two main drive belts immersed in oil to deliver a quieter, more efficient engine. As a result, the 98-horsepower Focus consumes 4.8 litres per 100km with carbon dioxide emissions of 109g/km.

The engine received 28 per cent more points than its nearest rival.

'If downsizing is the way ahead, there is currently no better example than this,' said British journalist John Simister.

'Same power as the naturally aspirated 1.6-litre engine it replaces, and much punchier to drive.'

Meanwhile, the range extending 1.4-litre engine in General Motors' Ampera and Volt electric vehicles won the 'best green engine' category.

Both models' 150ps electric motors can cover up to 80km on lithium-battery power, but the 86ps petrol engine can add up to 570km of range without an extra charge or fuel.

Ferrari's 570bhp, 4.5-litre V8 engine in the 458 Italia won 'best performance engine' and 'above 4-litre' categories.

BMW won four categories, including the '3-litre to 4-litre' category for the 4-litre V8 in the M3; the '2.5-litre to 3-litre' for its 3-litre bi-turbo six-cylinder petrol block in the 1 Series M coupe, 335is and Z4 35is; the '1.8-litre to 2-litre' for its 2-litre twin turbo four-cylinder engine; and the '1.4-litre to 1.8-litre' category.