The German luxury brand confirmed at the 2012 Geneva motor show that it would expand the A3 range after showing an A3 sedan concept (pictured) at the same show last year. The sedan will be available in both left-hand- and right-hand drive.
The A3 sedan will serve Audi well in markets such as the US and China where four-door cars are popular, though Audi Australia says it will investigate the Audi A3 sedan for the local market.
The A3 hatch is not expected in Australia until the second quarter of 2013.
Audi unveiled the latest-generation A3 in Geneva, though it only displayed the three-door model. A five-door hatchback 'Sportback' variant will follow, along with a Cabriolet.
The Audi A3 sedan concept was 4.4 metres long compared to the 4237mm length of the three-door A3. Both body styles share a wheelbase of about 2600mm. The sedan's boot offers an extra 45 litres of luggage space - 410 v 365 litres.
The third-generation Audi A3 is similar in size to its predecessor but is lighter. The A3 is the first Volkswagen Group model to sit on the giant manufacturing group's 'MQB' modular platform that will eventually underpin more than 40 models by 2018.
Volkswagen's seventh-generation Golf, which will be unveiled at the 2012 Paris motor show in September, will sit on the same platform.
The Audi A3 will compete against higher-end variants of the VW Golf, as well as more direct luxury hatchback rivals such as the BMW 1-Series, Lexus CT200h and Mercedes-Benz A-Class.