What is a common consequence of a low oil level in an automatic transmission?

A common consequence of a low oil level in an automatic transmission is delayed shifting from neutral to drive or reverse. This occurs because the transmission fluid acts as both a lubricant and a hydraulic fluid, allowing for smooth engagement and disengagement of gears. When the oil level is low, there isn't enough fluid to build the necessary hydraulic pressure required for the transmission to function properly. As a result, shifting can be sluggish or delayed, leading to potential strain on the transmission components and a less responsive driving experience.

In contrast, the other options do not accurately describe the impacts of low oil levels. Engaging the wrong gear typically results from other mechanical or electronic issues rather than low oil. Increased engine noise could indicate problems in the engine itself rather than transmission fluid levels. Better fuel efficiency is also unlikely, as improper shifting or delayed engagement can lead to decreased performance and possibly higher fuel consumption.