The shock departure - understood to have followed a disagreement over future strategy - follows a period of significant expansion and development by the company - particularly in the UK corporate market.
Earlier this year Budget won the Environmental Initiative of the Year in the annual Fleet News Awards for a range of 'green' initiatives which included the UK's first commercially-run car-user club in Edinburgh.
Such developments have helped drive business and increased revenues and profitability in all areas of the company.
Following Sawers' departure, sales and marketing director Roddy Graham was on Tuesday promoted to deputy managing director reporting to Jean-Claude Ghiotti, president and chief operating officer of Budget International.
Before joining Budget, Sawers had spells with rival rental companies Hertz and Europcar.