SANTA MONICA, Calif. — As shoppers gradually move back into the market, one segment, in particular, that has gained what some may consider to be surprising ground is the midsize sedan category, according to Edmunds.com

Pushed to some degree by attractive new releases, midsize cars command 17.8 percent of the U.S. market right now, and have seen their share move upward each year since 2005, when it was only 13.3 percent.

"Speculation has long held that crossovers would cause serious erosion of the midsize sedan market, but sedans are remarkably popular with car-buyers today," explained Bill Visnic, Edmunds' AutoObserver.com senior editor.

"April and year-to-date sales show the segment on its way to perhaps some of its best results in a long while," he added.

While the Honda Accord and Toyota Camry still rank as the top-selling vehicles in the segment, two "less-established models" are among the leaders of the pack when it comes to year-to-date improvement from 2009.  

Sales for the 2010 Ford Fusion through April climbed more than 50 percent year-over-year, and the 2011 Hyundai Sonata's sales moved ahead 34 percent.

The new Subaru Legacy, which has been redesigned, saw its year-to-date sales rise 87 percent. Also showing significant gains were the Chevrolet Malibu, Nissan Altima and Volkswagen Passat, Edmunds.com noted.

Meanwhile, sports cars have been slow to sell.

Granted, there has been a silver lining in that the Chevrolet Camaro and the Ford Mustang are engaged in a "healthy sales race," and that April was a "record sales month" for the Dodge Challenger.

However, the struggles in the segment have outweighed the bright spots.

Chevrolet Corvette's year-to-date sales are off to a worse start than the first four months of 2009, a year they eventually hit a half-century low for full-year sales. Edmunds.com said the Mazda Miata has had one of its worst years yet, while the Mazda RX-8 is "barely selling" and might receive the axe.

The Mercedes-Benz SLK roadster and Nissan's 370Z and GT-R models have seen their sales so far in 2010 fall by more than 40 percent versus "terrible" year-ago figures. Moreover, Porsche has experienced year-over-year softening throughout its entire lineup, Edmunds.com noted.

"Muscle cars are moving okay, but the rest of the sports car market is stuck in neutral," Visnic stated. "A 1,000-unit-per-month pace for a given sports car is becoming the norm, leaving some to wonder how long some automakers will — or can — support such frivolities, the cost-saving advantages of increased platform-sharing notwithstanding."