Zimmer

Zimmer is the owner and chief designer at Zimmer Automobil-Maschinenbau in Germany and also the designer and builder of the various incarnations of the Batmobile.

Zimmer works with Lucius Fox and Batman but under the impression that Fox and Batman are defrauding Bruce Wayne.

Zimmer charges top dollar for his work, constructing the Batmobiles himself and smuggling them out of Germany to Gotham City via a dummy corporation founded by Fox and funded by Wayne Enterprises.

Before Arkham Knight Incident
Fox and Batman personally flew to Germany to inspect the latest Batmobile design. German criminals got wind of the prototype technology incorporated into the design and kidnapped Fox and Zimmer for access to it but Batman rescued both of them in a high speed sportscar chase.

Trivia

 * The character Zimmer is obviously based on the german movie composer 'Hanz Zimmer' who is notable for composing the music to Christopher Nolan's 'The Dark Knight Trilogy'.