At a time when the subway system is severely overcrowded and straining to improve service, every schedule tweak is intimately felt, and one rider’s gain is inevitably viewed as another’s loss. At the same time, outlying neighborhoods are increasingly the most affordable places to live. But the commutes can be grueling. On a Monday morning, a trip from Coney Island to Herald Square in Manhattan takes about 55 minutes — if the trains are running on time.

The express service — an earlier version of which ended in 1987 when the route received major repairs — would save its riders nearly three and a half minutes on average during their morning commute, and some riders would shave off as much as seven minutes, the authority found. Local riders would lose more than a minute on average each morning.

Bringing the express back has been discussed on and off for some time, and Mayor Michael R. Bloomberg, a political independent, pushed for express trains during his 2009 re-election bid.

In a new report, the authority recommended moving forward with the express service, arguing it would benefit riders in southern Brooklyn with the longest commutes. But the change would require approval from the authority’s board, and the heated conversation over the proposal is likely to continue.

“This is just the start of the process, in which we will actively engage all of the communities that are affected,” Kevin Ortiz, a spokesman for the authority, said.

Mayor Bill de Blasio, a Democrat, was a longtime Park Slope resident, and the F train is the closest subway line to his home there, though he tends to travel by car. His office declined to say where the mayor stood on the proposal.

For F express service to work, Mr. Lander said, the authority would have to add more trains on the line — something it says it cannot do.