Mmm! The Ford Focus 1.0-litre will be here in March 2012.

Mmm! The Ford Focus 1.0-litre will be here in March 2012. But, what is the point of having such a small engine in a family car? The key is to understand the difference between 'displacement' and 'power'. The '1.0-litre' refers to the cubic capacity of the cylinders – not the power output. Two engines with the same displacement can, therefore, have very different performance figures. The Mercedes-Benz SLK, for starters, is available with a 1.8-litre 204PS engine. In contrast, the Vauxhall Astra 1.8 SRi only produces 140PS. So, despite having the same displacement - the sports car is more powerful than the Vauxhall.

Furthermore, the latest developments ensure that respectable performance can be squeezed from engines with small displacements. As such, Ford's 1.0-litre three-cylinder unit produces either 100PS or 125PS. This is comparable to a traditional 1.6-litre, but they return 58.9 and 56.5mpg respectively. Emissions are 109 and 114g/km, which is excellent.

Graham Hoare, European Executive Powertrain Director based at Dunton, said: "This is the third addition to our acclaimed EcoBoost engine family. Joining the 1.6-litre and 2.0- litre EcoBoost engines which span 150PS to 240PS, this 1.0-litre EcoBoost signals a new era of downsized, super frugal engines for the sub-130PS segment. During development our UK engineers focused on improving thermal efficiency and reducing friction of the engine's internal moving parts, especially during warm-up."

If you are unconvinced consider this; Formula One cars will soon have 1.6-litre engines.