United States registrations of new convertibles have increased 63% over the past six years, The Car Connection (TCC) website said, citing figures from RL Polk & Co. In a summer feature article comparing a variety of models, TCC said that convertible sales reached 310,595 in 2001, up more than 10% over 2000, and the first time that drop-top sales have surpassed 300,000 vehicles in 30 years.