That's true about a loose spare possibly flying around after impact, but if your a little adventurous like me chk. e-bay or do a google salvage yd. chk for a MB DONUT SPARE SLK 320. I bought one from a totaled 2004 SLK & it works beautifully when you apply air pressure yet when it's collapsed it sits tucked neatly below the height of the seat back by more than 6 inches lower when stored upright in the trunk area. You can even create your own brace & thru bolt it to the floor if laid flat. Many ways around it!! The bolt holes are an exact. Good Luck