I play the tuba in several groups. It appeared to me when I did the test drive, that the behind the seat cargo area in the Smart would be sufficient to store my instrument while travelling between gigs. I base this on a comparison of the behind-the-rear seat storage of my wife's Pontiac Vibe, which looked similar in size to what I would estimate the 8'8" American Fortwo version to be. My horn has a 19" diameter bell and I travel with a soft sided case. Also, I am a powerlifter/bodybuilder weighing in at about 265lbs(5'10") and I think it would be a fun visual to climb out of this little car and drag my horn out of the back! Of course if it doesn't fit, I have the ability to put it in the passenger seat, like I did years ago when I drove a Ford Festiva. Anyway, there's my challenge and my thinking-comment if you wish, ignore me if you don't!