In terms of impact on fuel mileage, idling ranks near the bottom of the list of factors affecting fuel economy. This is not to say that idle time should be ignored. The cumulative effect of small improvements can be very significant. Idling, unless it is necessary to maintain a comfortable driver environment or provide PTO (power take-off) power, is unnecessary. With much less management time commitment and training effort, reducing vehicle speed by 2 mph (3% change) can improve fuel economy by nearly 0.2 mpg.