New features include a 4-into-1 exhaust manifold and new engine controller to improve efficiency over a wider spread of engine operating conditions. Also introduced is diesel-style exhaust gas recirculation, which recovers exhaust heat to reduce warm-up times.
As well as the 97bhp 2.0-litre petrol engine, the Skyactiv-hybrid features an 81bhp AC motor and nickel-metal hydride battery.
And like the Toyota Prius hybrid, Mazda’s Skyactiv features a CVT automatic transaxle to split drive between the front wheels and generator/motor depending on driving conditions. Mazda claims the Skyactiv-hybrid drives with "seamless, linear acceleration".
Mazda only quotes Japanese-spec fuel economy figures, rating its new hybrid at 73mpg, about 60 per cent better than the 45mpg petrol-powered conventional Mazda 3.
One of three new Mazdas at Tokyo, the Skyactiv-Hybrid is joined by a Mazda 6 safety concept and a Mazda 3 powered by CNG (compressed natural gas).
The Mazda 6 ASV-5 safety concept is a showcase for a suite of safety sensors and vehicle-to-vehicle communication technology aimed at cutting accidents, particularly with city-centre trams.
Developed in a consortium with the University of Tokyo and Hiroshima Electric railway, a key feature is multiple channel data sharing between cars and trams, even down to details like turn-indicators, traffic signals and braking.
Historically, CNG is popular in Japan, particularly in Tokyo, because its clean combustion emits little NOx, the main component in the smog that can envelop Japan’s capital. The bulk of Tokyo’s taxi fleet, for example, has been CNG powered for exactly this reason.
Mazda's Skyactiv-CNG concept is based around a dual-fuel version of the 2.0-litre petrol engine fed by a 51-litre petrol tank and 75-litre CNG tank. It is unlikely to be sold in the UK, but may be imported to countries like Italy, where CNG is popular.
Read more 2013 Tokyo motor show news.