Audio 10's are not strong cd-r players. Normally the player will have trouble finding the beginning of the first track then play the rest of the cd without problems.
Mercedes offers no support for cd-r. Here is an excerpt from a Mercedes publication:
"Non-Commercial CDs in MB CD Units:
Programmable compact discs such as CD-R and CD-RW may not play correctly in MB USA CD players. If you encounter this problem with CD-R and CD-RW audio CDs in these players, verify correct operation of the player with a commercial CD. Due to variations in CD-R and CD-RW media and technical inconsistencies in programming them, MBUSA does not support their use in MB CD players."