North American DTM series that was scheduled to start between 2015 and 2016 based on the 2014 DTM/Class 1 regulations. As of 2019, a North American DTM series has yet to run, despite interest being shown by the North American sanctioning body to run DTM/Class 1, either as a series under IMSA sanction or possible integration into the sports car championship as a potential replacement for the GTLM/GTE class in 2022. The initial 2013 agreement to run a North American DTM Series was signed by IMSA's predecessor, Grand-Am Road Racing and did not take into account the subsequent merger of the sanctioning body with the rival sports car championship American Le Mans Series in 2014 to form United Sportscar Racing, now known as the WeatherTech Sportscar Championship. Race format When the DTM series returned, it used a similar format to the final season of the former DTM in 1996: two races of 100 kilometres, with a short break between them. In 2001 and 2002 there was a short race of 35 kilometres as well as a long race of 100 kilometres, which included one pit stop and points scored for the top 10 as in earlier seasons. From 2003 to 2014 there was only one race, which had a distance of about 250 kilometres, and two mandatory pit stops. For the 2015 season a new race format was introduced. Race weekend consisted of 40-minute (Saturday) and 60-minute (Sunday) races. On Saturday's race a pit stop was optional, while on Sunday's race a pit stop was mandatory and all the four tyres had to be changed. Both races had the same scoring system. In the 2017 season, both races of the weekend featured the same distance – 55 minutes plus a complete lap, with one race being held on Saturday, the other on Sunday. In both races, the drivers had to pit at least once for a set of fresh tyres. For the 2019 season the time limited race format was abolished and the series reverted to the fixed lap race format that was last used in 2014. However, after the opening round of the 2019 season, the series reverted the 55-minute plus one lap distance format due to issues with television broadcasts running longer than expected. DTM drivers The drivers have been a mixture of young and older drivers, including well known former Formula One drivers David Coulthard, Bernd Schneider,