Born in Adenau to restaurant owners, Schmitz grew up within the Nürburgring Nordschleife — her family's hotel and restaurant, the Pistenklause, sat in the basement of the Hotel am Tiergarten in Nürburg. All three Schmitz sisters began racing, but only Sabine pursued it professionally. She trained as a Hotelfachfrau (hotel management graduate) and a sommelière before committing to motorsport. She later also qualified as a helicopter pilot.
Schmitz built her reputation entirely around the Nordschleife. Racing under her married name Sabine Reck, she won the 24 Hours Nürburgring in both 1996 and 1997 in a BMW M3 Group N, co-driven by local veteran Johannes Scheid — making her the first woman to win a major 24-hour race outright. She also competed in CHC and VLN endurance racing events, claiming the VLN endurance championship in 1998.
In 2006, she partnered with Klaus Abbelen in the Nürburgring VLN endurance series, driving a Porsche 997 for Land Motorsport. The pair finished third in the 2008 24 Hours Nürburgring. She estimated that over the course of her career she had driven around the Nordschleife more than 20,000 times, adding approximately 1,200 laps per year.
Her day-to-day role on the circuit was as a driver of the BMW M5 "ring taxi" — a high-speed passenger experience service that brought her into contact with thousands of motorsport enthusiasts. Her familiarity and flair earned her the nicknames "Queen of the Nürburgring" and "the fastest taxi driver in the world." She ceased driving the ring taxi in 2011. Her own company, Sabine Schmitz Motorsport, continued to offer advanced driver training and ring-taxi rides from a Nürburgring base.
Her favourite sections of the circuit were the Schwedenkreuz (Swedish Cross) and the Fuchsröhre (Fox Hole) — the latter lending its name to the bar-restaurant she ran in Nürburg from 2000 to 2003 after her divorce.
In 1995, Schmitz contested the South African AA Fleetcare Super Touring Championship, competing as Sabine Reck in an E36 BMW for BMW SA Motorsport alongside teammates Deon Joubert and Shaun Van Der Linde. The campaign proved difficult; she was consistently outqualified and outpaced on circuits she did not know, and a mid-season crash at Killarney with Toyota driver Mike White left her with neck injuries and a damaged right knee, forcing her to miss three consecutive meetings. She finished last in the Class A standings with no wins, poles, or fastest laps and did not return for 1996.
She also made appearances in the World Touring Car Championship, though the Nürburgring remained the centre of her competitive identity.
Schmitz's first British television appearance came in 2002 on Jeremy Clarkson: Meets the Neighbours, where she drove Clarkson around the Nordschleife in the ring taxi. Her breakthrough on Top Gear came in December 2004 (Series 5, Episode 5), when — after coaching Clarkson to a 9 minutes 59 seconds lap in a Jaguar S-Type diesel — she dismissed his time with the now-famous line "I tell you something, I do that lap time in the van." She then lapped the same car in 9 minutes 12 seconds, beating him by 47 seconds. The film crew could not keep pace and resorted to using a Jaguar S-Type R piloted by Jaguar test driver Wolfgang Schubauer as a chase car.
In a subsequent episode (Series 6, Episode 7), Schmitz drove a Ford Transit diesel van around the Nordschleife, missing Clarkson's earlier Jaguar time by only 9 seconds. In 2008 she appeared in a Top Gear vs. Germany team challenge alongside fellow D Motor presenters Carsten van Ryssen and Tim Schrick.
Since September 2006, Schmitz had co-hosted D Motor on the German DMAX channel, taking on head-to-head challenges — Ferrari 360 against a 1200 hp race truck, Formula Renault car against a race sidecar — and she also made appearances on Fifth Gear.
In February 2016, the BBC confirmed Schmitz as one of several new co-presenters for the revamped Top Gear, alongside Chris Harris and Rory Reid. She made recurring appearances on the programme in the seasons that followed, becoming a familiar face to a new generation of viewers.
In July 2020, Schmitz disclosed via Facebook that she had been suffering from "an extremely persistent cancer" since late 2017. She had undergone treatment and reported improvement before relapsing, and was beginning a new course of treatment at the time of her announcement. She continued to appear on Top Gear while battling the illness. Schmitz died at a hospital in Trier on 16 March 2021, aged 51.
Following her death, the Nürburgring posthumously renamed the first corner of the Nordschleife loop the "Sabine-Schmitz-Kurve" in her honour — a fitting tribute to a driver who had come to embody the spirit of the circuit more than any other. As the first woman to win a major 24-hour race outright and a media figure who brought the Nürburgring to global audiences, Schmitz remains one of the most recognisable names in German motorsport and a pioneering figure for women in racing.