It is actually quieter (in terms of wind noise) and less windy in a convertible with the top down than it is in a coupe or sedan with the windows rolled down, particularly if you have the wind deflector.
On the highway I drive with the top up and the windows up but on a nice day the great roads we have in Berkshire County (Western Massachusetts) are perfect for top down cruising.
Route 2 Hairpin Turn
North Adams, Mass
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2010 M3 E93, 2009 Cayman S, Porsche GT2, 1969 Camaro Z28, 1964 Jaguar E-Type, Caterham Super 7 (track car), 1957 Thunderbird, 1954 Jaguar XK120, 1958 Corvette, 1955 MGTF, Superformance 427 Cobra, 2009 Ferrari F430, 1955 Chevrolet Nomad, 1965 Shelby GT350, Porsche Cayenne Turbo, 1963 Corvette Split Window Coupe. 2012 BMW 750Lix