A '2.3' (aka. "Two point three") is your typical middle-class white 30/40-something year old trophy wife
who's entire life revolves around her social image, her children, and driving her over-sized shiny new 4x4 through crowded suburban streets.
Also used to refer to the family unit that middle-class Australia fell into in the late nineties, when the average number of children per family was 2.3. These families are excessively affluent, social-status obsessed, and are usually seen in the suburbs of the inner-eastern region of Melbourne, Australia (such as 'Toorak', 'Camberwell', 'Glen Eira', 'South Yarra', 'Kooyong',etc). Vehicles driven by the female of these families are sometimes known as 'Toorak Tractors', referring to the 4x4/4WD 'tractors' that never see a spec of dust on them, and are used solely for transporting 2.3 children around the suburbs. No practicality is attributed to the use of these vehicles, as they aren't that much safer than your average family-sized stationwagon.
"Bloody 2.3's, I wish they'd stop driving those toorak tractors around the neighbourhood."