Automatic Engine Start/Stop

“Idle reduction means more money in my pocket by not burning fuel and less engine wear and tear.”

An owner/operator

Automatic engine start/stop systems provide the fleet owner with a way to reduce idling by turning the main engine on and off as required for heating and cooling when the driver is resting. They use the onboard HVAC system to cool the cabin and start up the main diesel engine only when cooling or heating is needed to maintain a temperature, shutting the engine down when the need is met. They can also keep the engine warm and charge the batteries.

Adopters of automatic start/stop systems have benefitted from needing to include little additional componentry and from having their truck’s batteries recharged. However, the system does not completely remove the need for idling, as the systems require the vehicle to idle some of the time.


Few additional components are required alongside automatic engine start/stop systems

If used with a Clean Idle engine truck, the truck can idle without violating idling regulations

Automatic engine start/stop systems recharge the vehicle’s battery, unlike some other idle-reduction solutions


Noise and vibration from stopping and starting the engine can disturb the driver’s sleep

Idling is still required, creating additional wear on the main engine, although less than without idle reduction

Introduction to Idle Reduction

Common Fleet Strategies

Automatic engine start/stop systems are one of the available anchor technologies of an overall idle-reduction strategy.

  • Coupling an automatic engine start/stop system with a battery HVAC allows the battery to charge when the truck is stopped, thereby eliminating one of the downsides of battery HVACs, which is that they drain the battery.
  • Paired with a Clean Idle engine, automatic engine start/stop systems help fleets achieve their idle-reduction goals. Note: The vehicle should not be ordered with the non-adjustable mandatory five-minute timer because the automatic timer interferes with optimatl functioning of the start/stop system. The engine may need to run for more than five minutes to heat or cool, which would not be possible with a non-adjustable timer.
  • The addition of a fuel-operated air heater and additional insulation make the system more efficient in the winter.

What Others Are Saying

Executives from 11 for-hire truckload carriers were personally interviewed to find out about their idle-reduction practices. No single technology was used by all 11 of the fleets, but five have automatic engine start/start systems on their vehicles.

Large Fleets

In conjunction with Michelin, the study team surveyed 200+ members of Michelin’s Fleet Forum. When asked what idle reduction technology they would purchase, 21.6% said automatic engine start/stop systems. Survey respondents preferred diesel APUs and fuel-operated air heaters as the most beneficial idle reduction technology

Internet Fleet Survey

Internet Owner-Operator Survey

Decision-Making Tools

There are already a wide variety of payback calculators for any given idle-reduction solution. In an effort to meet the industry’s need for more information, we have also developed a high-level payback equation to aid fleets in choosing the right combination of technologies.

Available Systems

Some systems only monitor the battery’s state of charge or engine temperature, while the fully-featured versions will also monitor sleeper temperature to provide heating and cooling. Once the vehicle’s engine is on, the vehicle’s HVAC system will warm or cool the sleeper just as it would if the truck were driving down the road. They perform the work of a block heater and battery charger without the need for outside power.


Truck manufacturers provide numerous options when it comes to idle reduction and there are many suppliers of idle-reduction technology. No single truck manufacturer is capable of engineering, testing, sourcing, producing, and servicing the full range of available idle-reduction options.

Only one truck manufacturer currently offers an automatic start/stop system, although they are available from multiple suppliers.


Automatic engine start/stop systems are a simple solution to reducing idling, but they may not meet idling regulations in some areas. When coupled with a Clean Idle engine, the vehicle equipped with an automatic engine start/stop system will be in accordance with idling regulations. Automatic engine start/stop systems need to be purchased without the tamperproof five-minute timer, which does not allow idling beyond a five-minute limit.