DaimlerChrysler UK has given 12 months notice to all 156 dealerships and plans, by the end of this month, to inform the groups it will offer new agreements.
A meeting of the Mercedes dealer council has been called for Tuesday, January 16, and manufacturer executives are expected to be barred.
Disgruntled dealers have been liaising through a website: www.mbdealers-speak.com
Wm Jacks has been informed it will lose its Mercedes dealerships at Sunningdale and Newbury inBerkshire. They are believed to have a combined turnover of around £30m.
DaimlerChrysler has not revealed its plans, though dealers are speculating over a possible Daewoo-style manufacturer-owned network.
Other possibilities are awarding major territories to a few selected dealer groups or focusing on online sales.
One Mercedes dealer said: "The arrogance of the manufacturer is beyond belief. It is a tragedy for dealers with small businesses who have done a good job for Mercedes and will lose their livelihoods."