Conventional wisdom suggests that rolling down windows and turning off the A/C during summer driving can help improve fuel economy. However, a group of SAE International engineers hope to enlighten drivers about this misconception.
The members of the group's Interior Climate Control Standards Committee have authored a paper that acknowledges the heavy energy-consuming A/C system but reports that the increased drag created by the open windows counteracts the improved fuel economy of cutting off climate controls.
The impact of A/C use on a vehicle's fuel economy can be as much as 30 percent for full A/C use versus turning off the system, according to the report.
Read the full report here.