Idle-management technologies create an opportunity for increased fuel efficiency by switching off the primary traction engine when the vehicle is stationary for extended periods (i.e. idling). This may occur during pick-up and deliveries, and during long periods without acceleration. (In passenger cars, similar systems operate even during short periods of idling, such as when stopped at traffic lights.) Fuel savings and emissions reductions arise from the cuts in total engine running time for a given route or delivery.

Application relevance

Idle management technology is primarily an OEM feature fitted to new vehicles and is particularly suited to light-duty urban application drive cycles with significant stopping and starting (such as urban areas). Long periods of idling to power cabin accessories on articulated trucks (hotelling) is not as common in Australia as it is in North America, but drivers of rigid pick-up and delivery trucks often leave vehicles idling unnecessarily. As a result, there is deemed to be a high level of relevance to the Australian transport situation.

Passenger and light commercial vehicles are starting to incorporate engine stop-start technology. However, the nature of the diesel engine in heavy vehicles limits the application of idle-off technologies to long periods of standby only, owing to heat stress issues.

Potential benefits

In light commercial vehicles, idle management engine technology presents a potential for 5–8% fuel savings, and a corresponding reduction in GHG emissions from the sector.

Potential idling reductions in heavy vehicles are difficult to quantify as they relate to driver behaviour and vary significantly from fleet to fleet and driver to driver

Air quality is also improved with reduced idling, as regulated pollutants are in higher concentrations during unloaded engine operation.

Key implementation considerations

The nature of the duty cycle must be considered prior to implementation of idle-off devices. In the wrong applications (infrequent stop-start) an acceptable fuel saving and payback period may not be achieved.

Examples of implementation

Isuzu article

This article discusses the new idle-off technology introduced as standard in one model of Japanese light commercial truck from Isuzu (Green Car Congress 2006a). In late 2006 Isuzu released a non-hybrid ELF light truck suitable for urban delivery which features an automatic idling stop and start system as standard. This vehicle is not currently available in Australia, although Isuzu has trialled the NMR85 hybrid model which features the technology.

For the full report, see Fuel for Thought – Identifying potential energy efficiency opportunities in the Australian road and rail sectors (opens in a new window) PDF 1.5 MB.