Mazda to release new stop-start

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Introduction

Like every other car maker, Mazda is under pressure to reduce its cars' average fuel economy. The Japanese manufacturer's own target is to cut consumption by 30% in the next seven years. That ambitious objective will be met by the development of new engines and the implementation of new technology, such as the company's own stop-start system, called SISS.

What is it?

SISS is short for Smart Idle Start Stop, which doesn't quite give away what makes it so special. After all, BMW currently fits stop-start to several of its models and other companies have utilised the function in the past. Where as all other systems rely on a heavy duty starting motor, Mazda's innovation is to use combustion itself to get the engine restarted.

The idea only works in petrol engines that are equipped with direct injection, as the fuel can be injected in a precise quantity to the cylinder in which the piston is in the best position for combustion to initialise before the spark plug ignites the fuel-air mix. Mazda claims that this system, in conjunction with the starting motor, restarts the engine in half the time BMW's does.

How does it drive?

Our early first drive was at the wheel of a current shape Mazda3 development prototype, so it was a little rough around the edges, but the SISS system was fully functioning. Like BMW's system, SISS requires the driver of a manual car to take the car out of gear and take his foot off the clutch when the car is at a standstill before the engine will shut off. For many drivers this will require a small change to their in-city driving style, but it's not difficult to master. The reward is complete peace and quiet while waiting for the lights to go green. Mazda's system does restart the engine quickly and with little noise, though it seems to take a fraction longer to stop the engine than BMW's version of the technology.

Planet hugger or planet mugger?

The first model to feature SISS will be the all-new Mazda3 powered by a 2.0-litre DISI (Direct Injection Spark Ignition) engine. This car doesn't arrive in Europe until 2009 and it won't be a large seller in a market dominated by diesel models. However, the USA and Japan still prefer petrol power, so it's an important development in the grand scheme of things. More importantly, Mazda has a whole range of new DISI engines under development, all featuring the stop-start functionality. Once it is rolled out across the range it undoubtedly assists reducing emissions and fuel consumption, though more so in an urban environment.

Verdict

It's likely that more and more car makers will employ versions of stop-start technology in the future in a bid to reduce their cars' fuel consumption and emissions. Mazda's new SISS features a clever new method for quickly restarting the engine, which should make it easier for customers to accept its usage.

Shane O' Donoghue

Wednesday September 17