I bought an ML63 6.2V8 in November 2017. The starter "felt lazy" so took it up the motorway - 200miles later - no improvement. The charging voltage after 200 motorway miles was an indicated 12.4V on the dashbord. So changed the battery for a new MB from dealer in March 2018. No improvement. So changed the alternator - new MB from dealer in June 2018. Charging improved to 13.4V to 13.7V on the dashboard. When measured with a Fluke, it is over 14V. 2 things: 1) Starter still "dips speed" on cranking-turnover - even with a warm engine before ignition... 2) Very puzzling: when you "blip the throttle" - voltage goes down before increasing? How?