Lugers can approach speeds as high as 90 mph or 144.8 kilometers per hour.
In the most recent luge world championships, the winner had an average speed of 81.3 mph (130.8 km/h), according to The Washington Post. In comparison, the four-man bobsled team that won at the last world championships had an average speed of 78.7 mph (126.7 km/h) and the winner at the skeleton world championships had an average speed of 71.9 mph (115.7 km/h).
The Guinness World Record for street luge is 101.9 mph (164 km/h) and was set in 2016 by American Mike McIntyre.
You can figure out more about luge at the 2018 Winter Olympics in PyeongChang here.