Changes to BMW's iconic 3 series line bring more power and torque with lower fuel consumption and emissions while coupé and convertible have have had minor design changes and interior enhancements. The automaker is also adding a new 320d EfficientDynamics saloon to the revamped UK line due for launch in March, calling it the 'cleanest' ever 3 series.

The new version has an 'official' EC test cycle combined fuel consumption of 68.9mpg and CO2 emissions of just 109g/km yet can accelerate from rest to 62mph (100km/h) in eight seconds. BMW GB said it is the first premium car with CO2 emissions under 110g/km and expects it to appeal to business users due to its predicted low lifetime running costs; its low CO2 emissions reduce taxes paid by company car drivers.

The third generation coupé and fourth generation convertible together account for about a third of 3 series volume in the UK. The updated 2010 models have new front and rear lights, revised 'kidney grille', new front air dam, rear valance and side rocker panels, a twisted chrome band around the grille 'kidneys', new lights with white LED corona rings, indicators and side repeaters and an illuminated 'eyebrow'. A new front air dam with single air intake is trimmed with matt aluminium fins.

New all red rear light clusters have LED light bars and the rear bumper is restyled.

There are new standard wheel designs (plus a new optional 18-inch alloy) and three new exterior colours.  Inside, Dakota leather is now standard on all UK coupé and convertible models and there is a new anthracite bamboo trim material.

The M Sport variants, which in turn account for 65% of 3 Series coupé and Convertible sales in the UK have also been revised with a new front spoiler, a new 19-inch M Sport wheel and a new colour of mineral white exterior colour option.

Prices start at GBP27,845 delivered.

Coupé and convertible models have a new I4 diesel engine option with 7hp more power (184hp) and 30Nm more torque (380Nm), boosting acceleration and reducing fuel consumption and CO2 emissions.

There are also detail changes to other engines offered across the range, to reduce consumption and emissions and lower the amount UK owners must pay in annual road tax.