Fantastically good point you bring up...
For some reason, modern (Australian) cars are getting bigger and bigger and wider and wider...yet anyone who looks at modern and recent carpark design will notice that carparks are getting narrower, and the distance (width of lanes) between one row of parks and the other is getting narrower as well, making it more difficult to swing into a park. The business can fit in more customers cars, but it makes it harder to park...I know for an example at our local K-Mart, the new underground carpark is set up for nothing much bigger than an Astra or Mazda 3 or 6...our VX Lumina has had quite a few interesting moments trying to negotiate very tight turns into car parks there...
I would imagine this is going by the standard logic that with rising petrol prices, you would think car makers would be going for smaller vehicles.
Go to a (shock, horror!) Japanese car makers showroom...any of them...or European makers for that matter...you will see that in relatively small cars, they can package a quite amazing amount of space inside the vehicles.
I am afraid that in the next, say, five years, I can see Holden and Ford facing a crisis like their mother companies in the USA...the management will think that the public loves bigger and bigger cars...the trouble is that the public does love bigs cars...but economic reality means that people, the majority, will come in off the street and look at a new Commodore and say "cool", but then walk right on by to actually purchase the Astra or something...