Question: What German automotive marque does the high-performance aftermarket tuning company Brabus specialize in?

Context paragraphs:
Gemballa: Gemballa is a tuning company based in Leonberg near Stuttgart, Germany, which was founded by and named after Uwe Gemballa in 1981.  They provided aftermarket parts mainly for Porsche.  In May 2010, the Gemballa factory was seized by German authorities and shut down following the disappearance of Uwe Gemballa who was later found dead.  CEO Andreas Schwarz and investor Steffen Korbach were able to buy the brand rights and name rights from Gemballa in August 2010 under the new name GEMBALLA GmbH.In 2016 Steffen Korbach became the sole CEO of the company and Alexander Schwarz stepped down.  Reportedly Korbach also took over the shares in the company from his former partner Schwarz.

Brabus Rocket: The Brabus Rocket produced since 2006, is a series of modified vehicles produced by Brabus, a German high-performance vehicle company.

Smart (marque): smart Automobile (stylized and marketed as "smart") is a German automotive marque and division of Daimler AG, based in Böblingen, Germany.  It ranges in microcars and subcompacts, primarily the Fortwo and Forfour with its primary assembly plants located in Hambach, France and Novo Mesto, Slovenia.  Marketed in 46 countries in Asia, North and South America, Africa, Australia and Europe, production of the Fortwo had surpassed 1.7M units by early 2015.

Spiess Tuning: Spiess Tuning is the common identity of Siegfried Spiess Motorenbau GmbH, a motor vehicle engine tuning company based in Ditzingen, Baden-Württemberg, Germany.  Today Spiess Tuning is most famous for its Formula 3 motor racing engines based on the Opel Family II and two iterations of Volkswagen R4 engines.

RE Amemiya: RE Amemiya Car Co Ltd (有限会社RE雨宮自動車 , Yūgen Kaisha Āru-ī Amemiya Jidōsha ) is an automotive tuning company from Chiba, Chiba Prefecture, Japan founded by Isami Amemiya.  Amemiya has made a name for himself tuning rotary engines since 1974 and has become a pioneer in tuning rotary-powered Mazdas. Thirty years later, first on the street and later in the Super GT series, Amemiya has left its mark in the tuning and motorsports worlds for rotaries.

Brabus: BRABUS GmbH, founded 1977 in Bottrop (Ruhr Area), Germany, is a high-performance aftermarket tuning company which specializes in Mercedes-Benz, Smart, Tesla and Maybach vehicles.  Brabus became the largest Mercedes tuner, other than Mercedes-AMG which became a DaimlerChrysler affiliate in the 1990s.

Evans Tuning: Evans Tuning, LLC is an automotive engine tuning, and aftermarket modification shop that specializes in the reprogramming of engine control units (ECUs), to provide a smooth driving experience and safe engine conditions after modifications to a stock automotive configuration have been performed.

GReddy: Trust Company Ltd. (株式会社トラスト , Kabushikigaisha Torasuto ) is a Japanese automotive aftermarket company specialising in performance tuning parts for cars.  The company is widely known for its subbrand of tuning parts GReddy and the turbochargers under this brand.

Brabus E V12: The Brabus E V12 is a tuned Mercedes-Benz E-Class made by Mercedes-Benz tuning company Brabus.  It was succeeded by the Brabus Rocket which is based on the Mercedes-Benz CLS.

Audi Performance and Racing: APR LLC is an American automotive engineering and motorsport company that offers aftermarket performance products for cars built by the Volkswagen Group, including Audi, Porsche, SEAT, Škoda and Volkswagen.  Audi Performance & Racing was founded in 1997 by Brett Augsburger and Stephen Hooks, automotive engineers looking to offer aftermarket upgrades for Volkswagen Auto Group cars.  Their first product was a ECU software upgrade for the 1997 Audi A4 1.8T, but the company soon expanded its product line to include exhaust and turbo systems.  APR engine tuning products use proprietary software for reading and writing to Bosch Motronic engine control units.

Supporting paragraphs: Brabus Smart (marque)
Answer: Smart