1963 Chevrolet Impala bench seat with period famale model

To look at automakers' lineups these days, it would appear that America's large car market is enjoying something of a resurgence. After all, Chevrolet has invested in a new Impala, Toyota has its new Avalon, Hyundai fielded an all-new Azera for 2012, and Nissan is presently working on a next-generation Maxima.

Yet, according to the industry forecasters at Polk, the market for mainstream big sedans is cratering. According to Polk's data, the large mainstream sedan segment has plunged from a 5.8-percent share of the US car market in 2008 to just 3.5 percent in 2012. That sales drop is enough to put this most American of car bodystyles behind the minivan segment, a market whose own sales slide has been comparatively well documented.

According to Polk, part of the reason for the shift is America's increasing appetite for smaller and more efficient vehicles, along with increased automaker emphasis on the midsize sedan segment, where more frequent redesigns and new technologies are becoming commonplace. In fact, Polk hypothesizes that at some point, family sedans like the Ford Fusion and Honda Accord may be subject to "re-definition" as America's largest non-luxury automobiles.

Despite the grim outlook, the firm's analysts believe that the "large car category will survive in the near term" thanks to forthcoming entries like the Chevrolet SS, Kia Cadenza and Volkswagen Phaeton, which Polk expects to return in 2015. On the premium side of the street, the picture looks somewhat better, with the number of big luxury players staying pretty much the same. Even so, sales of cars in the class from automakers like BMW and Mercedes-Benz has slipped from .76-percent to .46-percent of the total US sales market.