SOUTHFIELD, Mich. – U.S. automakers led by General Motors may lose share in their home market this year, a setback that might be assuaged by holding onto some of their gains against disaster-stricken Japanese rivals in 2011.

GM, Ford and Chrysler, coming off a year in which all three added share for the first time since 1988, may drop a combined 1.3 percent of U.S. market share in 2012, according to a Bloomberg survey of five analysts.

The U.S. automakers may each increase sales by less than the total market’s growth this year, according to all five analysts surveyed. While falling unemployment, rising consumer confidence and the need to replace aging vehicles will drive demand, increased Japanese output and improved competition from Korean brands and Volkswagen will test Detroit’s discipline on protecting profit rather than simply selling products.

“Market-share loss is never positive, but the U.S. automakers are still going to grow,” Jesse Toprak, an analyst at the auto-pricing researcher TrueCar.com, said in a phone interview. “They can’t lose sight of their new emphasis, which has been improving their cost structures, making cars people want to buy and selling the product instead of the incentive.”

Sales may rise this year to 13.6 million vehicles, the average estimate of the analysts, from 12.8 million in 2011, continuing the recovery from 2009’s 27-year low of 10.4 million vehicles.

GM, which regained global sales leadership last year, may fall to 19 percent of the U.S. market, from 19.6 percent last year, analysts estimate. Ford may drop to 16.3 percent from 16.8 percent and Chrysler may decline to 10.5 percent from 10.7 percent. The three gained a combined 2 points of share last year, according to Autodata Corp.

Asia’s largest automaker, Toyota, may capture 13.8 percent of the U.S. market this year, from 12.9 percent last year, and Honda may take 9.5 percent, from 9 percent, analysts estimate.

Aside from their tsunami-and flood-stricken performance last year, combined market share for Toyota and Honda will be the lowest since 2005, according to the Bloomberg survey, which interviewed analysts from LMC Automotive, AutoPacific Inc., Edmunds.com, TrueCar.com and Kelley Blue Book.