Mazda harnesses new tech for better economy

Mazda gambled with the latest Mazda3, betting customers would pay more for cars loaded with impressive features such as a head-up display and active cruise control.

The brand has now doubled down with a new engine option exploring that theory further.

Dubbed Skyactiv-X, the engine is a 2.0-litre four-cylinder petrol unit with remarkable efficiency made possible by mild hybrid tech combined with a clever approach to combustion that aims to harness the best characteristics of diesel and petrol engines.

Diesel engines work by compressing fuel and air until the mixture explodes under duress, while petrol engines use the flame of a spark plug to ignite the fuel.

Mazda’s new motor aims to create the best of both worlds, combining a diesel’s high cylinder pressures with the computer-managed burn of a petrol engine, a process it describes as “Spark Controlled Compression Ignition”. A small supercharger allows it to run leaner than naturally aspirated alternatives, often mixing small amounts of fuel with roughly twice as much air as regular engines.

The result is a car that uses 5.5 litres of petrol every 100km of driving, about 10 per cent less than its existing 2.0-litre engine. An hour-long test drive returned 6.5L/100km — average economy stemming from sub-five-litre thirst on highways and mid-sevens in town. That’s impressive, if not earth-shattering economy.

The current Volkwsagen Golf uses 5.6L/100km. Maximum outputs of 132kW and 224Nm slot it between the Mazda3’s existing 2.0-litre (114kW/ 200Nm) and 2.5-litre (139kW/252Nm) engines. The technology isn’t cheap.

While a regular 2.0-litre “G20” Mazda3 starts at about $29,250 drive-away, the new “X20” engine is only available in top-end Astina trim, priced from about $45,000 drive-away with a manual transmission, or another $1000 with the six-speed auto favoured by the vast majority of customers. That’s $3000 more than the top-end 2.5-litre “G25” Astina model.

A requirement to use premium fuel also blunts the X20’s appeal, diminishing the economic gains. Petrol prices on the day of our test drive were such that a prospective owner driving 10,000km per year might save $40 a year by choosing the new model over the 2.5-litre.

Toyota’s Corolla hybrid comes at a $2000 premium over the standard version while neardoubling the Mazda’s comparative fuel savings.