Already previewed by the recently-revealed top-shelf 1 Series M Coupe, the 'regular' Coupe and Convertible models get updated lights, including a new LED strip up front and a similar update to the tail-lights.
Other exterior updates include new-design 17- and 18-inch alloy wheels, along with two new paint options: Marrakesh Brown and Vermillion Red.
The front bumper also comes in for a modest update, gaining reshaped air intakes to channel air through the front wheel arches and across the face of the wheels, reducing wind resistance.
The 135i gets a new rear differential, optimised for improved performance and fuel consumption, along with a new rear lip spoiler for increased downforce at high speeds.
New interior features include a new leather-wrapped sports steering wheel with shift paddles, along with an M-branded version that also offers shift paddles.
Interior updates are rounded out by new button graphics and chrome highlights to the centre console, along with improved connectivity for iPod control and Blackberry devices.
Speaking with TMR today, BMW Australia's Piers Scott confirmed that both the 1 Series M Coupe and the updated 1 Series Coupe and Convertible models "will arrive in Australia around third quarter, next year".
Mr Scott also confirmed that BMW's all-new X3 medium SUV is scheduled to arrive in March, with details to be confirmed early next year.