Since coming into motor racing in 1965, after many years competing in speedboats and motor cycling, Quester has been identified with the BMW marque for the bulk of his long career - not surprisingly, perhaps, since he had married Julianna, the daughter of Alexander von Falkenhausen.
Dieter really came to prominence by winning the Austrian touring car championship in a BMW 1800 in 1966, and his sideways driving style in the factory BMW then took him to two consecutive European touring car titles in 1968-69. He was also part of BMW's largely unsuccessful Formula 2 programme, though he did manage a victory at Hockenheim at the end of 1970. Quester switched to a March for a season of Formula 2 in 1971, and performed well, winning the Lottery GP and scoring five second places. It was around this period that, frustrated at being unable to get a Formula 1 ride, he more than once seriously considered retirement, but he carried on and eventually drove a rented Surtees in the 1974 Austrian GP.
Subsequently concentrating on sports cars and saloons, he was European G2 touring car champion in 1977 and a regular in the BMW Procar series of 1979-80, while throughout the nineties he has been a permanent fixture in BMW touring cars in the European, German and Austrian championships, as well as competing in a BMW M5 in the IMSA GT3 class in America in 1996 and 1997.
- 1958-1961: European Champion outboard speed boats.
- 1963-65: Motorcycle Racing (BMW, Norton, NSU).
- 1966: First contact with BMW. Austrian Touring Car Champion and winner of the Int. BMW Motorsport Trophy (BMW TISA).
- 1967: BMW factory driver.
- 1968: European Touring Car Champion (BMW 2002 TI). 4th European Hill Climb Championship (BMW Prototype).
- 1969: 3rd: European Hill Climb Championship (BMW Prototype). European Touring Car Champion (BMW 2002 TI, 2002 Turbo).
- 1970: 4th: F2 European Championship (BMW Dornier F2).
- 1971: 3rd: F2 European Championship (March-BMW F2).
- 1972: 4th: European Sports Car Championship 2 ltr (Chevron - BMW).
- 1973: 2nd: European Touring Car Championship (BMW CSL 3.5).
- 1974: F2 Team Surtees (Surtees TS9). F2 European Championship Team Harper Hong Kong (March BMW F2).
- 1975: European Touring Car Championship (BMW CSL 3.5).
- 1976: World Championship for Makes, 2 overall wins (BMW CSL G5).
- 1977: European Touring Car Champion (Alpina BMW 3.5).
- 1978-79: World Championship for Makes, 3 overall wins (BMW 320 G5).
- 1980-83: Procar Championship (BMW M1).
- 1983: European Touring Car Champion (Schnitzer BMW 635 CSI).
- 1984: Endurance races for Team Fitzpatrick (Porsche 956).
- 1985: European Touring Car Championship (BMW 320). Sports Cars for Team Goodrich (Lola Mazda).
- 1986: European Touring Car Championship (BMW 320 G5). Endurance races Team Goodrich (Porsche 962). 24 Le Mans, Team Sauber (Sauber Mercedes).
- 1987: European Touring Car Championship (BMW M3). 24hr Le Mans Team Sauber (Sauber Mercedes).
- 1988-91: Int. German Touring Car Championship DTM (BMW M3).
- 1989: Endurance races Team Spice USA (Spice Pontiac).
- 1992: European Touring Car Championship CC (BMW).
- 1993: Austrian Int. Touring Car Champion (BMW M3).
- 1994: STW Championship (BMW 320).
- 1995: IMSA Championship (BMW M3). Organisation together with Team PTG of the first steps for BMW in the US GT racing scene.
- 1996: IMSA Championship Team PTG (BMW M3 GT).
- 1997: IMSA Championship Team PTG (BMW M3 GT).
- 1998: US Sportscar Championship Team PTG (BMW M3 GT). Italian Touring Mastercup, Team Duller Motorsport (BMW M3).
- 1999: ALMS Championship Team PTG (BMW M3 GT). Italian Touring Mastercup Team Duller Motorsprt (BMW M3 G N).
- 2000: ALMS Championship Team RWS (Porsche GT3). FIA GT Championship Team RWS (Porsche GTN). Italian Touring Mastercup Team Duller Motorsport (BMW M3).
- 4 Times European Touring Car Champion.
- 41 24hr and 12hr races (Spa, Le Mans, Nurburgring, Daytona, Sebring). 4 overall wins at Spa.
- Over 600 race starts. More than 250 podium results.
- One of the first drivers to create a special fitness program and diet for motor sport activities.