Pursuit of the Best Possible Fuel Economy

pursuit of the best possible fuel economy

Cummins is continuing in its pursuit of the best possible fuel economy harnessed with optimum driveability and performance from its X15 engine in both the current Euro-5 and future Euro-6 guises. Paul Matthei was invited to experience the down-speeding of each engine variant from the driver’s chair on a return run from Coffs Harbour to Newcastle.

It’s a fairly simple and predictable equation: within reason the lower the rpm of an engine the better the fuel economy. And this is precisely the basis of eco-driving, keeping the engine operating within the peak torque band as much as possible. 

However, as noble a cause as eco-driving is, the benefits must be balanced with the practical implications of running a time-sensitive freight haulage business, and there’s none more time-sensitive than those running east coast inter-capital B-double operations. 

As the age-old saying goes, time is money and saving a few litres of fuel at the expense of half an hour of trip time often doesn’t cut the mustard in these types of operations. It’s virtually an unwritten law that these drivers must strive to maintain the velocity of their machines at close to the legal speed limits at all times to ensure they arrive at their destinations on time. 

As the sole vendor engine supplier to Kenworth, Australia’s most popular heavy-duty truck brand, Cummins knows only too well that the enduring popularity of its engines amongst truck operators is due in a large part to their reliability and durability. But the way in which the company backs up its products in terms of maintenance and servicing procedures also factors in to the equation. 

Put simply, these engines do the job well and they continue to do it well, usually for the projected life of the truck, provided they are furnished with the required levels of maintenance, both scheduled and preventative.

In common with every other truck engine producer, Cummins must comply with stringent exhaust emissions regulations that in this country are currently set at the Euro-5 level. However, Euro-6 is already on the distant horizon with the smart money suggesting an implementation date of around 2022. 


pursuit of the best possible fuel economy
Mike Fowler, Cummins’ On-Highway Engine Director


As such, Cummins has decided to go on the front foot and prepare its engines for the stringent new standard ahead of time. Not only that, it is also applying the principles of down-speeding to its current Euro-5 products in order to not only provide a comparison base for its Euro-6 engine development, but also to give customers the opportunity to gain the best possible fuel economy from the current power plants.

Key to refining and optimising performance parameters and fuel efficiency of its engines is Cummins’ close collaboration with Eaton in developing the Integrated Powertrain Package consisting of the Cummins X15 engine and Eaton UltraShift Plus 18-speed double-overdrive automated manual transmission (AMT). 

The electronic controls are what Cummins calls ADEPT (Advanced Dynamic Efficient Powertrain Technology), with the latest version known as Integrated Powertrain Calibration (IPC). This system provides an unprecedented synergy between the two powertrain components that ensures harmonious operation for maximised performance and fuel economy under various operating conditions.

Like anything though, optimum results don’t come easy and exhaustive testing and re-testing is required with different parameters such as rear axle ratios to come up with the best solution for particular applications. 


pursuit of the best possible fuel economy