According to the Britax Fit finder the Evolva Ultra 123 does not fit Mercedes A Class. As the Fit finder only relates to Stage 0/0+/1 seats does anyone know whether that only applies to the Stage 1 configuration and if in the Stage 2/3 mode , as a highback booster, it might yet fit ? Have also emailed Britax but wondered in the meantime if anyone had come across it .