Convertibles now account for less than 1 percent of the U.S. market.

Once perfectly acceptable as a family car, convertibles have seen their share of ups and downs over the last century. But sunny weather cars have seen their share of the market erode rapidly over the last few years as buyers have flocked instead to more practical convertibles.

According to Automotive News' research, convertibles currently account for a hair under 1 percent of the new car market. Last year, they represented about 1 percent of the market, but as recently as 2008 they took home just a bit under 2 percent overall.

While there's some strength at the upper end of the segment with cars like the megabuck Mercedes-Benz SL-Class and BMW 6-Series Convertible, automakers admit that there's not much upside to low cost convertibles any longer.

Through the first four months of 2013, the trade journal found that the best-selling convertible, the Ford Mustang, accounted for just 6,421 registrations in the U.S. At about 25 percent of total Mustang sales, that represents a decent chunk of the pony car's volume, but a large number of those droptops were likely sold as less-profitable fleet transactions. Rental fleets, particularly in sunny weather markets, remain chock full of convertibles like the Mustang and Chevrolet Camaro.

Speaking of the Camaro, it was the strongest-selling droptop in 2011 when it was re-launched as a convertible, but it has taken a back seat to the Mustang since. According, R.L. Polk data, these were the 10 best-selling convertibles through April of 2013:

  1. Ford Mustang - 6,421
  2. Chevrolet Camaro - 4,751
  3. Volkswagen Beetle - 4,305
  4. Mercedes-Benz SL-Class - 2,380
  5. Mercedes-Benz E-Class - 2,206
  6. BMW 328i - 2,108
  7. Chrysler 200 - 1,980
  8. Fiat 500 - 1,920
  9. Mazda MX-5 Miata - 1,822
  10. Porsche Boxster - 1,686