Are Australian Vehicles Getting Bigger?
ABC Radio Sydney called me and asked essentially:
`Are Australian Cars Getting Bigger?'
The short answer is 'No.'

Using data from the Federal Chamber of Automotive Industries that was once freely available online, and is now behind a paywall, I have produced graphs illustrating the Australian vehicle market. The data show among the passenger cars: medium, small, light, and micro are all gaining in proportion of passenger cars, rising from half the passenger car market to 83% since 2000.
But
`Are Australian Vehicles Getting Bigger?'
The answer here is 'Yes.'
As will be no surprise to Australians, or North Americans (See Canada data), the share of Sports Utility Vehicles has exploded since the beginning of the Millennium from about 13% to 39%, and now more SUVs are sold each year than passenger cars.


This trend, which mirrors that in the US, helps explain Ford's recent decision to exit most of the passenger car business in the US.
Now 50% of 70% is 35% (small cars share of all vehicles in 2000) while 80% of 38% is 30% (small cars share of all vehicles in 2017), so the share of small and medium cars of all vehicles is falling. But the total market of vehicles sold in Australia is still increasing from 787,000 in 2000 to 1,189,116 in 2017, and 30% of cars sold in 2017 is more than 35% of cars sold in 2000, so there are still more in terms of total number of small and medium cars sold in 2017 in total than 2000, even if it is a declining share of the market.
The Australian government also conducts a Motor Vehicle Census and just as the number of new cars sold each year rises with population growth, the total number of vehicles is also rising. This differs from the US, which has more or less peaked in cars per capita, and perhaps cars. I graphed this data for NSW for selected years (this data, is also, inconveniently, not in one place)

The reason for more SUVs vs. large cars are speculative. That is, why do people now prefer SUVs and not station wagons or big cars? It's not as if people actually do a lot of off-road driving.
One is the idea of the extreme trip. Sometimes (say once a year or even once a month) a very large car would be useful. So instead of renting the specific vehicle when they want it, SUV-owners buy the vehicle they would use 1% of the their trips (or 0.05% of their time - since cars are only used 5% of the day anyway, and at rest the remainder, sleeping more than even cats), but which is too large 99.95% of the time.
One answer is the car Arms Race. In a taller car, the driver can see farther ahead (drivers are less likely to have their view obscured), which lets tall vehicle drivers anticipate better. It makes drivers feel safer, which they are for themselves, even when they are not for others.
More people are killed because of SUVs and light trucks, in the US, Michelle White estimated in 2004 "For each 1 million light trucks that replace cars, between 34 and 93 additional car occupants, pedestrians, bicyclists, or motorcyclists are killed per year, and the value of the lives lost is between $242 and $652 million per year." Presumably the same logic holds in Australia.
Increasing the mass of vehicles on the road doesn't do society any favours from an energy consumption, or air pollution perspective either. And of course, larger vehicles use more space, consuming more land in parking lots (which are now often restriped to accommodate more massive vehicles) and roads, where the width of lane consumed by larger cars rises, providing less manoeuvrability for other cars.
With the rise of autonomous vehicles, and especially vehicle sharing, the right sized vehicle will be summonable by app, so when travelers need the specific type of car for a large trip with many people, they can get it. The rest of the time, drivers will be able to use a car fit for purpose, one that holds one person for a one-person trip, and two people for two-person trips, and so on. This opens up the potential for skinny cars, enclosed electric cycles, and many other appropriate vehicles, which take up less road space, making it even easier to improve the environment for other road users, including walkers and bicyclists.
Toyota iRoad one-passenger concept cars, image courtesy Toyota.
DEFINITIONS: Passenger Motor Vehicles Passenger vehicles are classified dependent on size, specification and average retail pricing. Selected vehicle types will be assessed on footprint defined as length (mm) x width (mm), rounded, as follows: Sports Utility Vehicles Vehicles classified as Sport Utility Vehicles (SUV) meet the FCAI criteria for classifying SUV vehicles based on a 2/4 door wagon body style and elevated ride height. Vehicles typically will feature some form of 4WD or AWD, however, where a 2WD variant of a model is available it will be included in the appropriate segment to that model. Light Trucks Vehicles designed principally for commercial but may include designs intended for non-commercial applications. Heavy Trucks Vehicles designed for exclusive heavy commercial application. Car sizes: Micro Hatch, sedan or wagon with a footprint < 6,300 Light Hatch, sedan or wagon with a footprint range 6,301 - 7,500 Small Hatch, sedan or wagon with a footprint range 7,501 - 8,300 Medium Hatch, sedan or wagon with a footprint range 8,301 - 9,000 Large Hatch, sedan or wagon with a footprint range 9,001 - 9,500 Upper Large Hatch, sedan or wagon with a footprint range 9,501 > People Movers Wagon for passenger usage, seating capacity > 5 people Sports Car, coupe, convertible or roadster SUV Sizes: Light Duty 3,501 - 8,000kg GVM Medium Duty => 8,001kg GVM & GCM < 39,001 Heavy Duty 8,001kg GVM & GCM > 39,000 Light Truck Sizes: Light bus < 20 Seats 8+ seats, but less than 20 seats Light Bus > 20 Seats 20+ seats Vans/CC <= 2.5t Blind/Window vans and Cab Chassis <= 2.5t GVM Vans/CC > 2.5–3.5t Blind/Window vans and Cab Chassis between 205 and 3.5 tonnes GVM Pick-up / Chassis 4x2 Two driven wheels, normal control (bonnet), utility, cab chassis, one and a half cab and crew cab Pick-up / Chassis 4x4 Four driven wheels, normal control (bonnet), utility, cab chassis, one and a half cab and crew cab Heavy Truck Sizes: Light Duty 3,501 - 8,000kg GVM Medium Duty => 8,001kg GVM & GCM < 39,001 Heavy Duty 8,001kg GVM & GCM > 39,000