2017 Kia Rio vs Mazda 3

What's the difference?

As it becomes clear they're swimming in a shrinking pool, fish instinctively take up the struggle for available space and oxygen. Suddenly, all bets are off and only the strongest and most competitive manage to rise above an increasingly agitated pack to fight another day.

And so it goes in the Australian new car ecosystem. The 'light' category is still one of the largest in market, where the likes of Hyundai's Accent, the Mazda2, and Toyota's evergreen Yaris live. But the line on the sales chart is ever so consistently heading south.

Year-to-date sales for light cars under $25k are down no less than 20 per cent, and that's on the back of 16 per cent drop over the course of 2016. Meanwhile, medium SUVs are up close to 10 per cent.

So, clearly our automotive tastes are changing, but that big school of little cars is still spinning itself into a frenzy, with an intensifying battle for market share resulting in new and upgraded models offering a seemingly endless stream of advanced technology and ever-lengthening standard equipment lists.

Enter Kia's Rio hatch, the brand's global best-seller, with claimed annual sales "approaching 500,000", which is undoubtedly a big number. But in Australia, the Rio is a middle order player in a light car field of around 15 determined competitors.

Which means the new fourth generation Rio, launched here in January this year, is critical to Kia's chances of grabbing a larger slice of the rapidly diminishing light car pie.

Not surprising then, that the entry-level S model boasts upgraded multimedia connectivity and enhanced safety tech, not to mention improved dynamics and more space. Sounds good, but is it enough to get a jump on the light car big guns?

For over a decade, the Mazda3 has been part of a three-way battle for supremacy in the Australian small car market. The 2004 original threw the felines among the flying rats when launched, transforming the then-dowdy 323 into a stylish, well-equipped, and well-priced contender for Toyota's segment-dominating Corolla, and later, Hyundai's value-packed i30.

In 2017, the battle is still raging. Late 2016 saw a mild update to Mazda's flagship hatch and sedan range to add a few bits and bobs to the its already finely-judged specification. The Corolla stayed pretty much the same, and just this month Hyundai dropped what is now an annual tradition, an absolute cracker of a new car. This time, the all-new i30.

As you can see, Mazda has never had it easy, and it's a testament to the 3's quality, style and ever-growing reputation that it continues to hold its own in the top three.