Sytner began racing in the early 1970s in Formula Ford before establishing himself in the Clubmans formula for front-engined sports cars. He moved into touring cars in the 1980s. Although he was already a successful BMW dealer by this stage, his first British Touring Car Championship campaign was conducted not with BMW machinery but with Tom Walkinshaw's TWR team, which ran the Rover SD1 Vitesse. The partnership did not last; Sytner and Walkinshaw fell out and Frank departed mid-season.
Joining the BMW contingent, Sytner drove the 635 model run by Ted Grace Racing. In 1983 he protested the legality of the TWR Rovers, an action that ultimately cost Steve Soper the championship title. The following year Sytner entered a semi-works BMW 635 under the Sytner Racing banner and finished second in class behind Andy Rouse.
After a year away from the series in 1986, Sytner returned in 1987 with Prodrive, which had taken over the factory BMW contract and was now running the new BMW M3. He took several wins during the season. In 1988 he won the BTCC title outright with Prodrive in the M3, the championship victory coming at a point when the series was evolving toward what would become the two-litre super touring formula.
In 1990 Sytner returned to contend the new two-litre super touring class, winning the class title and finishing second overall despite a competitive battle with 1989 champion John Cleland in the works Vauxhall Cavalier. The pair were involved in a controversial collision at the Birmingham Superprix late in the season. Sytner's final BTCC season was 1991, after which he retired from the sport to concentrate on his expanding dealership business.
In the years following his BTCC retirement, Sytner moved into historic car racing, competing in both sports cars and historic Formula One machinery. He became particularly associated with a Penske chassis in historic single-seater events. At the Historic Grand Prix of Monaco in 1997 he won the Ferrari Sportscar Pre-1959 class in a Ferrari 250. In 2002 he won the F1 Grand Prix pre-1966 race at the same event in a Brabham BT4. He participated in the BTCC Masters race at Donington Park in 2004, finishing eleventh. In April 2011 he suffered a suspected heart attack while racing a Lola at the Donington Historic Festival.
Together with his brother Alan Sytner, who had at one time owned the Cavern Club in Liverpool, Frank founded his first car dealership in Nottingham in 1968, specialising in BMW products. Sytner BMW became the first UK dealership to market the Alpina brand after securing an exclusive contract in the early 1980s. Throughout the 1990s the business expanded through acquisitions, eventually encompassing around 45 dealerships selling prestige marques including Mercedes, Ferrari, Lotus, and Jeep. The natural synergy between his dealership focus and his racing activity with BMW machinery shaped much of his competitive career in the 1980s.