You guys would be surprised at how cold you can drop the top. My friend with the Miata will put his top down as long as it's 40 degrees or higher. I've seen quite a few hard-core roadster people drive around with the top down in 40-45 degree weather. I believe the trick is, top down, keep your jacket on, turn up the heat, and you're good to go (even roll up the side windows if you want).