All-new Mazda3 with ‘i-stop’ technology

On sale since 18 May, the all-new Mazda3 range incorporates a distinctively fresh bodystyle that portrays a more powerful and emotional design, plus a richer expression and a more dynamic stance.  Now the 20-model line up is completed by the arrival of two Mazda3 2.0 Sport models (hatchback and saloon, priced from £18,025 OTR), featuring 151ps petrol engines and innovative ‘i-stop’ (Smart Idling Stop System) fuel-stretching technology.  The system, which automatically switches off the engine, on engaging neutral, whenever the car is stationary (or travelling below 2mph) for more than a few seconds and restarts the engine when the driver simply depresses the clutch, delivers significant fuel-saving benefits for retail and fleet customers – without distracting from this model’s truly sporty driving experience.

“The all-new Mazda3 2.0 Sport with our exciting ‘i-stop’ technology uniquely delivers both performance and cost savings to fleets, company car and individual drivers,” comments Peter Allibon, Mazda Fleet and Remarketing Director.  “In recent times, a 2.0 Sport petrol model may not have been the obvious first choice for a city-bound company car driver.  However, the introduction of our highly efficient i-stop technology means that our latest model may change all that.  The new Mazda3 2.0 Sport with i-stop will be the right choice for city drivers who still want to experience power and performance from their company car out on the open roads.

“Indeed, the Mazda3 2.0 Sport with i-stop makes cost-effective performance driving accessible to a totally new group of drivers.  The revised DISI engine is remarkably sophisticated with sequential valve timing and a variable induction system to ensure powerful torque throughout the rev range.  For employees who regularly experience stop-start motoring in urban environments, our fuel-sipping i-stop technology mated to this 2.0 engine is the sensible money-saving choice,” adds Allibon.

Fitted with Mazda’s i-stop technology, the new Mazda3 2.0 Sport delivers 16 percent fuel economy savings (mpg, combined cycle) over the outgoing model, with CO₂ emissions reduced up to 19 percent.  Drivers whose mileage is predominantly city-based can achieve even greater fuel-savings and the model’s official CO₂ rating (159g/km) falls below the benchmark 160 g/km capital allowance tax threshold, thereby enabling companies to maximise corporate tax savings following April’s changes to the system.

“The new Mazda3 2.0 i-stop falls into the 19 percent benefit-in-kind tax bracket in 2009/10 and with capital allowance benefits and first-class fuel economy the model represents the cost-effective choice for fleets and user-chooser company car drivers alike.  With i-stop helping to ensure CO₂ emissions are below 160g/km, it’s great news for fleet drivers,” concluded Allibon.

Mazda’s i-stop (Smart Idling Stop System) technology

The unique Mazda system, combining i-stop technology with the MZR 2.0 DISI direct-injection petrol engine, uses combustion energy to restart the engine quickly with only a little help from the starter motor in certain situations and without using much fuel.  To accomplish this, the positioning of the pistons and crankshaft, valve opening and direct petrol injection are precisely tuned with one another.  Unlike other stop-start systems, Mazda i-stop effectively ‘pauses’ the engine, rather than stopping it, so it is poised on ‘stand-by’ for a rapid restart in just 0.35 seconds.  This is made possible by the storage of the combusted fuel mix, which is ready to be ignited as soon as the driver depresses the clutch.

Assistance from the electric starter motor is only required at the very beginning of restart.  Initial ignition combined with an impulse to the crankshaft is able to restart the engine in an extremely smooth and fuel-efficient way – twice as fast as conventional start-stop systems.

In adopting this unique approach to restart, in addition to being quicker than conventional start-stop systems i-stop also adds to a feel of quality in having a minimal impact on both noise and vibration levels.

The i-stop system is activated when the car is started – although there is a ‘deactivate’ switch on the dashboard.  The fully automatic system is non-intrusive and not noticeable when driving after initial start-up.  Only when the vehicle first comes to a standstill and the driver depresses the clutch to engage neutral, does the engine shut down automatically.  A green indicator lamp in the instrument cluster shows that the start-stop system has initiated engine cut-off as planned.  When the car is stationary, no fuel is used.  To continue driving, the driver depresses the clutch and the engine starts up again automatically.

A unique solution developed solely by Mazda, i-stop capitalises on the advantages of direct-injection technology to restart the engine after stopping.  Once the all-new Mazda3 comes to a halt, the engine’s control module does not cut off the engine until the cylinder air volume of the compression-stroke and the expansion-stroke pistons are equal – putting the engine in an ideal restart position.  One cylinder remains in the combustion-stroke position and the restart process begins when fuel is injected directly into this cylinder, atomised then ignited, which causes the piston to move down.  At the same moment, the starter motor applies a small amount of additional momentum to the crankshaft.  Both these events together initiate an extremely quick restart of the engine.

To ensure reliable electric energy supply at all times, particularly during engine shut-off and restart, the Mazda3 2.0 i-stop has two batteries.  The main battery delivers the general energy supply, while the sub battery is used exclusively for starting the engine.  When i-stop shuts off the engine, illumination, the audio system and all other electric systems continue to work.  Even the climate control is still operating as usual – as long as the driver does not require the full cooling capability of the system – i-stop being clever enough to recognise comfort being more beneficial than engine shut-down.  In this case i-stop recognizes the need to restart the engine and reduces power to the air-conditioning momentarily as appropriate.  The function of all systems is not interrupted during engine restart.

The i-stop system does not initiate engine cut-off during the warm-up phase, helping the exhaust-gas treatment system to reach its optimal operating temperature quickly and to minimize emissions.  Similarly, if the car is on a hill with a grade of more than 14 percent, the engine continues to run for safety reasons.