sir ji mercedes is very easy on maintenance only if you can do some diagnostics based on codes. parts are cheaper compared to any other Toyota camry honda accord lexus sedans.
a school friend have a 2004 S 350 in lahore he uses that car as daily ride. out of his passion for cars he have a scanner. When needed he hires a reliable mechanic who work on his car at his home under his guide lines. so far 17 years and his vehicle clocked 280,000 kms with basic maintenance as per merc schedule. he source parts & items from uae.
@Xulfiqar @babarhyd can guide you nicely where to go for oem new parts of mercedes in karachi.