They're called convertibles or ragtops in the United States. In Europe, the topless cars are known as cabriolets. To the automakers, they translate into profits as sales of the pop-top vehicles have gone through the roof, according to the Associated Press. Convertibles are creating a little daylight in passenger car sales that had lagged those of sport utility vehicles in recent years but are now rebounding. Through the first four months of this year, sales of convertibles are up 28 percent compared with the same period a year ago, according to industry sales figures.