Mazda6 mules are out there somewhere being tested right now for a planned debut in early 2012. The vehicles feature an entirely reworked suspension, an advanced six-speed automatic transmission and a multi-purpose platform that will underpin several new Mazda models. Mazda sources say that the new 6, with its advanced platform and new range of engines, should be future-proofed for upcoming emissions and safety standards for at least a decade after its launch, but Mazda's approach to engineering engines that will meet future regulations is rather unusual. Or, as Autocar puts it, the company's Sky mills are "uniquely engineered."

At launch, the Mazda6 will be available with at least two entirely new Mazda-developed Sky engines. According to the company, both the 2.2-liter Sky D diesel and the 2.0-liter Sky G gasoline engines will offer best-in-class fuel efficiency, but both engines achieve their fuel-sipping status via unconventional designs. The diesel unit has a relatively low 14:1 compression ratio and meets 2013 Euro 6 emissions regulations, but does so without expensive NOx traps and therefore is cheaper to build than many of today's Euro 5 diesel mills. The gasoline engine is normally aspirated, but its high 14:1 compression ratio gives it much-improved low-end torque. Key to the engine's design is its oversized 4-2-1 manifold. This manifold boosts power, but also requires more packaging space. Both engines conform to Mazda's global powertrain strategy and, as such, they will see widespread use in numerous company vehicles in the coming years.

[Source: Autocar]