THE battle to stay on top of the new car best seller list shows no sign of relenting - and Ford has provided an efficiency boost to help keep its evergreen Fiesta model at the pinnacle.

It comes in the form of mild hybrid technology and though the difference it makes isn't massive, the system can boost fuel economy by between five and ten per cent.

In the Fiesta Hybrid's case there is a belt-driven starter/generator in place of the standard alternator, enabling recovery and storage of energy usually lost during braking to charge a 48-volt battery pack.

Ford says the company is committed to offering an electrified version of every passenger model it sells in the UK and will have grown its range of electrified vehicles in Europe to 18 before the end of this year.

The beauty of hybrid tech of course is that it doesn't have a negative impact on handling and performance - something absolutely essential with a car like the Fiesta ST-Line.

Not to be confused with its hot hatch stablemate the full-blooded 2.0-litre Fiesta ST, the ST-Line still comes packed with sporty touches and edgy styling but is much more affordable.

And when it comes to younger drivers in particular, the savings in both purchase price and insurance costs can be considerable.

Beneath the ST-Line's bonnet is a 1.0-litre EcoBoost petrol engine producing 125PS, the result of which is acceleration of 0-62 in 9.4 seconds and a top speed of 125mph.

Those figures may not be anything out of the ordinary but when allied to the Fiesta's sports suspension, pin-sharp steering and superb grip the result is a spirited, exciting driving experience.

The downside of that firm suspension though is a shuddery ride quality for rear seat passengers on anything other than a smooth surface.

That said, the ST-Line remains a small car of considerable appeal, with plenty of space up front, enough for two adults to relax in the back and a decent-sized boot too.

The cabin has a classic Ford layout but more minimalist, the ST-Line trim bringing touches like drilled alloy pedals, a leather flat-bottomed steering wheel, piano black inserts and an eight-inch touchscreen for the sat nav.

The price tag of £21,160 isn't exactly bargain basement but you do get some nifty features like self parking, selectable driving modes of Eco, Normal and Sport - a large body-coloured rear spoiler and a heated windscreen.

Ford has also updated its SYNC 3 communications and entertainment system to be more intuitive and easier to use, with a new user interface and larger buttons on the colour touchscreen.

There's also Apple CarPlay and Android Auto compatibility for the premium Bang & Olufsen sound system plus a wireless smartphone charging pad.

And safety kit includes everything from blind spot warning lights in the external mirrors - something every manufacturer should provide on all their vehicles - to lane keeping assist.

Overall though Ford has done a fine job in making the Fiesta ST-Line look and feel both sporty and upmarket.