Richard,
There is a lot of talk here about converting totally to EV vehicles, but like you are seeing there in Oz, the support infrastructure isn't there, especially where distance travel is concerned. Plus, there is no shortage of backyard gearheads like myself who still like working on our own machines and making them better somehow.
With my background in engineering, I'm used to turning wrenches, and have been doing it since I was a teenager. I would still own gas vehicles just because I know my way around them.
For my personal tastes in what I do to my vehicles, I always try to improve performance, but keep fuel economy at the best level with the lowest possible emissions. This means I do everything I can to get better ignition with a more thorough burn to increase maximum combustion, (which equals more horsepower and lower emissions), and unrestricted air flow. And by all means, clean fuels are a must, meaning fuel with no additives if possible. Also, it's very important to provide the best lubrication to keep everything from wearing down and causing poor performance.
For example, my daily driver is a 2006 Chevy Impala LT trim package. It has 209,000 miles on it. I use the best synthetic oil and filters on it, and it performs like a champ. I get 20,000 miles on my oil with a filter change at every 10,000 miles. Every time I change filters or oil, it is still golden in color. This means there is no blow-by, and the internals of my engine is clean. It's rated at 22 MPG, but I get closer to 30 MPG with it, so I think I'm on to something here. I'll be doing something similar with the truck after I've had a chance to evaluate the true condition of the engine in it.