I have a W211 280CDi estate (March 2006). I unlock the car with remote key function as per usual. Central locking performs as expected. I put the key in ignition and the safety interlock unlocks (small familiar sound associated with this, I can then knock the Auto box out of Park with foot on foot brake). However in Park position as per usual when starting, when I turn the key to start the engine there is no response whatsoever. The starter motor does not turn. Nothing happens. I get the full dashboard lights as usual with key in start postion. I get no warning notices on dash. I have now removed the main rear battery which is 8 years old and measure 12.45V (no load). I didn't check the voltage before disconnecting, maybe I should do? I am currently charging it. It is taking charge from a reasonnable battery charger. Prior to removing the battery I did try a disconnect and reconnect, waiting about 2 mins before reconnecting. The was no change when attempting to start. The car has been garaged with no use for several months with the rear battery disconnected at negative terminal. Yesterday I reconnected the battery and successfully started the car. I did 3 short journeys each of a few miles for which the car started ok. The car failed to start after a 4th journey of about 3 miles. Could anyone offer any advise as to what the problem is likely to be?