TINY turbos are changing the game for the modern motorist and Ford is leading the way with an engine which does exactly what it says on the box.

The one-litre, three cylinder EcoBoost engine in its lowest power output is a real eye opener.

It is powerful enough to hold its own in family-sized cars while delivering the same sort of fuel economy only diesels could offer not so long ago.

Developing 100ps the engine is being fitted in the latest Focus and in Ford's new B-MAX - a compact MPV with pillarless sliding rear doors enabling the easiest access to any car on the market.

We have just tried out the engine in the B-MAX and although it is a slightly heavier vehicle than the Focus, the 100ps EcoBoost suits the car well.

There is plenty of life throughout the rev range and with a top speed of 109mph and 0 to 60 time of 13.2 seconds it is not lacking in any department.

What is remarkable about this engine is the way it laps up the miles without drinking fuel.

On a drive from Cambridge through Suffolk - albeit over fairly flat countryside - the B-MAX averaged 55 to the gallon which is exactly what Ford claims.

In this day and age most drivers find it impossible to get anywhere near the official fuel figures but with this engine it is a realistic proposition.

Driven carefully and it is possible to eke out even more economy and on the return run we managed to see an average of 69mpg on the car's trip computer which beat the official combined figure by some 25 per cent. Such an increment is quite amazing, especially considering that this version is not fitted with a stop/start system.

In the B-MAX the 100ps EcoBoost engine is mated to a five speed manual gearbox and can be had in mid-range Zetec trim from £16,195. Its emissions are rated at 119g/km.

The Focus with the same engine is slightly more economical - Ford claims 58.9mpg with emissions down to 109g/km - and it's priced from £16,445.

The one-litre EcoBoost had already won Ford plenty of acclaim for its effectiveness and the engine is also available with added turbo boost delivering 120ps in the B-MAX and 125ps in the Focus, and despite the additional power the economy remains top drawer.

The engine - which is small enough to sit on a piece of A4 paper - will also feature in the latest version of the Ford Fiesta which is due on sale in the next few weeks.