title: List of leading Thoroughbred racehorses
context: It is common to compare racehorses on multiple factors such as their overall race record, the quality of the horses they beat and the brilliance of their wins. Comparison of raw times is generally unreliable between horses of different eras or even in different countries due to a variety of factors such as the racing surface and the pace at which the race is run. Timeform ratings, introduced in 1948,[1] and Beyer Speed Figures, introduced in the United States in 1992, are relatively recent attempts to compensate for such variables.[2] Thoroughbred Winning Brew holds the Guinness world record for the fastest speed for a Thoroughbred racehorse, at 70.76km/h (43.97mph) over two furlongs,[3] although Quarter Horses attain higher speeds over shorter distances than Thoroughbreds.[4] Looking at average speeds for longer distances may be misleading as many races are run with a slow initial pace followed by a sprint in the stretch drive.
question: How fast is the fastest horse in the world?
answers: 70.76km/h