The company has held credentials meetings with a number of undisclosed agencies and is drawing up a shortlist to pitch for the business. Porsche's in-house marketing team will be handling the review.
The move will come as a blow to the incumbent, Clark McKay and Walpole, which has held the consolidated account for the past six years.
The agency was appointed to both the above and below-the-line business following a competitive pitch in 2001 that saw the end of the car marque's relationship with Leagas Delaney.
Porsche is currently the world's most profitable car manufacturer, and recently reported first half pre-tax earnings of £954 million.
Its success is partly attributable to its recently increased stake in fellow German car brand Volkswagen, which it made last month in order to safeguard the company from a hostile takeover bid. The acquisition boosted Porsche's earnings by an estimated £355 million.
Porsche declined to comment.