MAZDA HAS RELEASED its first start-stop equipped model in its Japanese home market, debuting its i-stop technology in the all-new 2010 Mazda Axela (or Mazda3, as it's known in the rest of the world) today.
Start-stop systems such as Mazda's i-stop conserve fuel by automatically shutting down the engine during times when it would normally be idling, like when standing still at traffic lights. Because the car doesn't need to move, the engine doesn't need to run, therefore significant savings in fuel economy can be made during urban driving.
Mazda reckons its i-stop system can reduce fuel consumption by up to 15 percent over the previous model, and says the i-stop equipped Axela sips just 6.09l/100km on the Japanese 10-15 mode combined cycle.
Many automakers are adopting the fuel-saving start-stop principle in their new products, with Lamborghini even considering such a system for its next-generation supercars.
But what marks Mazda's i-stop system as being different from most others already on the market is in the way it re-starts the engine after shutting it down.
Rather than engaging the starter motor or using a belt-driven motor to get the engine spinning again, Mazda's i-stop instead halts the engine so that one cylinder is primed with a full charge of air and fuel and the valves closed.
When the ECU detects that the engine needs to be started again the sparkplug fires, igniting the captive fuel-air mixture and thus re-starting the engine.
The genius of the i-stop system is that it inflicts no additional wear and tear on the flywheel's ring gear, doesn't require a beefed-up starter motor and weighs no more than the standard 2.0 litre direct-injected four-cylinder upon which its based. It's also lightning-quick, restarting the engine in just 0.35 seconds.
So when will we see i-stop on locally-delivered Mazda3s? Unfortunately, cost is the one barrier to the technology being applied to Australian-spec 3s.
"It's something we are looking at, but at the moment we just can't get it to work in terms of a business case. It's just too expensive for us to introduce here at this stage," Mazda Australia spokesman Steve Maciver said to TMR.
"i-stop is something that we will continue to look at. Obviously with changes in exchange rates its going to be an on-going study for us, but at this stage it's a 'no'."