The all new Mazda 3

The 'all new' Mazda 3 shares its mechanical platform with the Volvo C30 and Ford Focus and the engines are basically carried over from the previous 3, with the sort of obvious tweaking that everyone in the car business now uses to boost power and cut emissions.

Your top hat, that is.

They have managed to convince us that old is definitely new again with a sweep of arrivals which are not much more than a new 'top hat' - industry-speak for the upper bodywork - over something recycled from an earlier model.

And we're not just talking about the homegrown Ford Falcon, which continues to power into the 21st century with an FG update which is - whisper it - not really too far forward from a facelift.

Now, before the Ford fans all fire up for a lynching, there is nothing wrong with a top hat tickle. It makes a car look new and fresh and it costs a lot less than the $1 billion-ish that a company like BMW spends on something completely new.

And it's not like the top-hat attack is restricted to Australian carmakers. Or family-friendly brands. Porsche did it when it switched from the 996 to the 997 model of its long-running 911. Volkswagen has also done it with the latest Golf, which it describes as the Mk6. But it has the same mechanical platform and roof and a bunch of stuff, which is why computer programmers would be more likely to call it Golf 5.1.

And now the arguments have begun over the 'all new' Mazda3.It shares its mechanical platform with the Volvo C30 and Ford Focus and the engines are basically carried over from the previous 3, with the sort of obvious tweaking that everyone in the car business now uses to boost power and cut emissions and economy.

So, what is new? And when is new? And does new really matter if the top hat looks fresh?

The arguments are racing in the car world, and around the world, and no-one has a definitive answer yet.

Oh, for the days of the Holden 48-215, which was truly new and set Australian on the road to a world of cars. The old Humpy celebrates its 60th birthday next week and it's time for a party and plenty of nostalgia.

But wasn't it just really some sort of Chevrolet which had been given a top hat tickle for Australia . . .?