Mazda's new stop-start technology, and its upcoming 2.2-litre turbodiesel engine, could improve performance while using less fuel. Shane O'Donoghuereports
THE OPPORTUNITY to drive the new 2.2-litre turbodiesel Mazda6 at nearly 200km/h, less than 10 minutes into our short journey, was a clear demonstration of why Mazda's European RD centre is based in the middle of Frankfurt - it's useful to have a stretch of derestricted autobahn on your door step.
Keeping up with the outside lane traffic was one of the objectives for Mazda's new turbodiesel engine, though interestingly this was not to be at the cost of fuel economy or emissions.
Despite growing in capacity, this top of the range version returns the same 5.6-litres/100km combined-cycle fuel economy and 147g/km of CO2 emissions as the current 2.0-litre engine manages in the Mazda6. That's despite boasting 182bhp and 400Nm of torque, a substantial increase over the current car's 138bhp and 330Nm.
On paper, this engine appears to be little changed from the 2.0-litre, with a moderately increased stroke equating to the larger capacity, but in fact it features a wealth of new technology, including 2,000-bar fuel pressure, reshaped turbine blades in the variable geometry turbocharger and a unique new diesel particulate filter.
Along with appreciably improved performance, the new engine is much quieter than the current 2.0-litre, noticeably so further up the engine speed range. Thanks to a new balancer shaft, it is smoother too.
Irish sales of the 2.2-litre turbodiesel Mazda6 will begin early in 2009, though it will be sold alongside the 2.0-litre initially. Eventually, Mazda will offer several power output versions of the new engine presumably with even less emissions and fuel consumption.
The subjects of reduced fuel consumption and less emission of "greenhouse gases" were central to our day in Frankfurt. Mazda's director of RD, Seita Kanai, was eager to tell Motors that his company has targeted a 30 per cent improvement in fuel economy across its range by 2015. Kanai admits that a fresh range of engines is required to achieve that ambitious target, along with new technology such as start-stop.
Mazda has developed its own start-stop functionality it calls Smart Idle Stop Start (SISS). Unlike the system used extensively on four-cylinder BMWs, SISS only works with direct injection petrol engines. That may sound limiting, but petrol still powers the vast majority of cars in the United States and Japan, despite Europe's continued move to diesel power.
Like other stop-start systems, Mazda's switches off the engine when the car comes to a standstill. The driver must take the car out of gear, and let the clutch out before this happens in the manual car. Upon pressing the clutch again, the engine restarts. However, Mazda claims that its SISS can restart the engine twice as quickly as BMW's version. The improvement is due to the use of the direct injection system to initiate combustion.
A sophisticated new crankshaft position-sensor monitors the precise location of each piston in its cylinder and when the command is given to stop the engine, the alternator is used as an engine brake to ensure that one of the pistons stops in a suitable place. On restarting, fuel is injected directly into the corresponding cylinder and ignited with the spark plug, hence assisting the starting motor and ensuring a quicker take-off.
Our short drive in a Mazda3 development mule confirmed that SISS restarts the engine very quickly and relatively quietly too - Mazda has also modified the starting motor to reduce noise.
Though initially only to be offered on manual models utilising a new 2.0-litre petrol engine, Mazda has already developed SISS for use with an automatic transmission and admits that it could apply stop-start to its diesel engines too, though obviously without the assistance of combustion on restarting.
The first car to offer the SISS system will be the next generation Mazda3, due to be displayed at the LA and Bologna motor shows later this year. In Ireland few customers will benefit from the SISS technology, as the 2.0-litre engine will not be a big seller.
However, in 2011 Mazda will launch a new range of four-cylinder petrol engines featuring direct injection and the stop-start technology.
When asked where Mazda will go from here with its powerplants, Kanai smiles and admits that, while they will keep an eye on electric and other forms of propulsion, he hopes his company will find solutions that still result in an exhaust note.
He points to Mazda's ongoing work on hydrogen-powered internal combustion engines as an example of how it can produce cars that live up to owners' expectations in a sustainable manner. Kanai's parting statement is telling though - he underlines the need for governments and every one of us to do our part in achieving this sustainability.