Ahead of the third generation Prius' launch in Japan set for mid May, Toyota has let it be known that its new eco champ returns as much as 38 km/L (equal to 2.63 L/100 kms) in Japan's domestic fuel cycle, coupled with exceptional C02 emissions of just 61 g/km.

Those are stunning figures to be sure, but just to put it into context that's in Japan's traditional 10.15 mode fuel cycle which has long been known to show hybrids in a pretty generous light.

In Japan's newer, tougher JC08 cycle that's now being phased in, meantime, the Prius is still exceptionally green with Toyota claiming 32.6 km/l (3.01 L/100 kms) with C02 coming in at 71 g/km.

Besides touting its green credentials, Toyota is, of course, taking a well earned swipe at the hot selling Honda Insight whose 10.15-mode showing in Japan comes in at 30.0 km/l (3.33 L/100 kms) or 26 km/l (3.9 km/l) in JC08.

With the Honda's C02 ratings at 77.4 g/km or 89.3 km/l, in the numbers game, at least, it already looks game set and match to Toyota and the new Prius' accomplishments look all the more impressive seeing that at 1.8-litre, it's several classes up on the little 1.3-litre Honda.

Once upon a time, the car industry competed on things like horsepower, top speed and 0-100 km/h. Now, with Prius vs Insight, clearly we have a Japanese eco slugfest that's set to go all the way.