Mercedes-Benz E-Class Cabriolet 2018 Owner's Manual page 60

Weight group 0+ (up to 13 kg and up to approx. 15 months)
Size class:
E
D
C
Weight group 1 (9–18 kg and approx. 9 months to 4 years)
Size class:
D
C
B
B1
Equipment: Left/right rear seat
ISO/R1 IL
ISO/R2 IL
ISO/R3 IL (1)
IL Suitable for ISOFIX child restraint systems according to the table in "Overview of the recommended child restraint systems", or if the
vehicle and the seat are listed on the child restraint system manufacturer's vehicle model list.
(1) When using a child restraint system of size category (ISO/R3), move the front seat to the highest position. Make sure that the seat
backrest of the front seat does not rest against the child restraint system.
Equipment: Left/right rear seat
ISO/R2 IL
ISO/R3 IL (1)
ISO/F2 IUF
ISO/F2X IUF
Occupant safety 57