Question: Günter "Bobby" Klass was a factory driver for a company that has been successful in many branches of motorsport of which most have been in what?

Context articles: Earl Bamber
Sven Müller (racing driver)
Outline of physical science
Günter Klass
Porsche in motorsport
Laurens Vanthoor
Andy Pilgrim
Patrick Pilet
Alexandre Bengué
Maxime Martin

Earl Anderson Bamber (born 9 July 1990) is a professional racing driver from New Zealand, currently competing as a factory driver for Porsche Motorsport in the FIA World Endurance Championship LMP1 class, the North American WeatherTech SportsCar Championship in the GT Le Mans class and the VLN Endurance Racing Championship Nürburgring.
 He is the 2014 Porsche Supercup and double Porsche Carrera Cup Asia champion.
 He is a double Le Mans 24 Hours winner, having won the 2015 24 Hours of Le Mans with Nico Hülkenberg and Nick Tandy and the 2017 24 Hours of Le Mans with Timo Bernhard and Brendon Hartley.
Sven Müller (born February 7, 1992 in Mainz) is a German racing driver currently racing for Porsche Motorsport as a factory driver.
 He is the reigning Porsche Supercup champion during 2017.
Physical science is a branch of natural science that studies non-living systems, in contrast to life science.
 It in turn has many branches, each referred to as a "physical science", together called the "physical sciences".
 However, the term "physical" creates an unintended, somewhat arbitrary distinction, since many branches of physical science also study biological phenomena and branches of chemistry such as organic chemistry.
Günter "Bobby" Klass (13 June 1936 in Stuttgart – 22 July 1967 near Florence) was a versatile German racing driver, competing in hillclimbing, rallying, and the World Sportscar Championship as factory driver for Porsche and the Scuderia Ferrari.
Porsche has been successful in many branches of motorsport of which most have been in long distance races.
Laurens Vanthoor (] (pronounced together as [ˈlʌu̯rənsfɑnˈtoːr]); born 8 May 1991) is a Belgian professional racing driver currently racing for Porsche Motorsport as a factory driver in the FIA World Endurance Championship.
 He currently resides in Waiblingen outside of Stuttgart.
Andrew Pilgrim (born 18 August 1956 in Nottingham) is a British-born racing driver, who became a United States citizen in 1998.
 He is a Cadillac factory driver at the SCCA World Challenge, where he resulted GT class champion in 2005, runner-up in 2007, 2008 and 2012, third in 2006 and 2013.
 He also resulted fourth in 2009 and 2010 with a K-Pax Volvo.
 Pilgrim was also a Corvette Racing factory driver from 1999 to 2003.
Patrick Pilet (born October 8, 1981) is a French professional racing driver currently racing for Porsche Motorsport as a factory driver in the FIA World Endurance Championship and other racing series.
 He has competed in major sports car endurance races like the 24 Hours of Le Mans, 24 Hours of Daytona, 24 Hours of Spa, 12 Hours of Sebring and Petit Le Mans.
Alexandre Bengué (born 22 December 1975 in Lourdes) is a French rally driver.
 Bengué was a factory driver for Škoda Motorsport in the World Rally Championship in 2005, before scoring two points finishes as a privateer in 2006.
Maxime Martin (born 20 March 1986) is a Belgian professional racing driver and son of four-time Spa 24 Hours winner Jean-Michel Martin.
 He competes in the DTM for BMW Team RMG.
 Martin has been a BMW factory driver since 2013, racing full-time in the American Le Mans Series for BMW Team RLL that season, as well as acting as BMW's DTM test and reserve driver.
 In late 2013 at BMW Motorsport's yearly review, Martin was confirmed as a full-time BMW DTM driver for the 2014 season.