I noticed for the first time today, a loud whinning noise when backing out of my drive. I did have the top down, and usually I go out the length of the drive in forward gear. Just wondering if this is a normal sound as I havent had my smart very long.
Yes, it is normal. Remember when cars had little quirks that endeared us to them? Welcome back to the good old days. We've gotten so used to sanitized near-perfection that any little noise concerns us.
My cab also "whines" in reverse, and the whine increases with increasing reverse speed (transaxle). As you have learned, the sound is more pronounced with the cab's top down. As David mentions above, the smart's tranny is definitely an "acquired taste." Vive la difference!