My 2007 Mercedes-Benz E220 CDI with 49,000 miles sometimes used to feel like it was trying to lurch forward while moving at low speed, without any change on the accelerator. For the last month it is shaking for a few seconds to and fro on starting, while the rev counter stays constant at 900rpm and does not show any fluctuation. What this could be? I tried using the Shell V-power diesel, Total Excellium Diesel and BP premium diesel but no change in behaviour. Is it any good using any of these two fuels or is it just a gimmick? Excellium is usually slightly less expensive of the three, BP being most expensive.