2015 BMW 3 Series update to offer three cylinders

BMW's updated 3 Series will be sold in Australia with a new three-cylinder engine, as well as the usual fours and sixes.

It's a brave move. The Bavarian brand is the first to move to triple power in the premium medium class.

The turbo 1.5-litre engine will power the 318i, entry point for the facelifted 3 Series line-up due to reach our showrooms in about October. It will take the place of the sub-$60,000 316i, which has a turbo 1.6-litre four.

Although smaller, the new triple matches the 100kW maximum power of the 316i.

The 3 Series triple does come with a power pedigree

But BMW's new triple is outclassed by the turbo fours of obvious competitors from Audi and Mercedes-Benz; maximum power of the base A4's 1.8-litre is 125kW, the C-Class's 2.0-litre produces 135kW. These numbers are likely to interest Australian customers more than the triple's sub-6.0L/100km fuel sipping figure.

Still, the 3 Series triple does come with a power pedigree. In tuned-up form, this is the same engine that powers the rear wheels of BMW's swift and stunning i8 plug-in hybrid.

Engines are the big story of this 3 Series update. Nearly everything in the range moves to BMW's newest engine family. As well as the petrol triple, there are new 2.0-litre turbo petrol and turbo diesel fours and a new 3.0-litre turbo petrol six. Only the turbo diesel six-cylinder, not offered here, is to be carried over from the current 3 Series.

The new engines are built around common 500cc modules. They've been designed for manufacturing efficiency. As well as sharing of parts inside the petrol and diesel engine line-ups, there's also 30 to 40 per cent sharing between petrol and diesel.

They've revised the basic standard and sports suspensions

There are some new names to go with these new engines. The 320i badge is retained, but the current 328i four is to be replaced by the 5kW-more-powerful 330i. Likewise, the 335i six is to be replaced by the 340i. This facelift will also bring changes to front and rear bumpers, designed to make the 3 Series look more snarly, and a new headlight design. Full LED adaptive headlights will be an option for the first time, too.

BMW engineers say they attempted to make the updated 3 Series a sportier drive. They've revised the basic standard and sports suspensions and have upgraded to two-valve variable shock absorbers in the switchable adaptive damping system.

Their aim was to improve steering precision and reduce body roll while cornering, without killing comfort.

BMW Australia isn't saying how much these new 3 Series models will cost until closer to their arrival date. But the prices need to be super sharp.

Like Audi, BMW is being brained by Mercedes-Benz in the premium medium category.

Check out Malcolm Flynn's video review of the BMW 3 Series: