July 24 (Reuters) - Porsche's CEO said on Wednesday the carmaker was more vulnerable to the recent aluminium supply shortage because of its high percentage of pre-ordered cars, low volumes and detailed car specifications.

"We have a high percentage of very exclusive cars which are not built to stock, which makes it more difficult to switch units," Blume said. We have very low volumes which brings us into the situation of single source."

The carmaker was working at full speed to restore volumes but would not be able to compensate for the interruption to production of several weeks caused by the shortage, CFO Lutz Meschke added. (Reporting by Victoria Waldersee Editing by Madeline Chambers)