test rider (2016–present) KTM confirmed Kallio as their lead test rider on 27 October 2015, for the upcoming MotoGP project, in preparation for the season. Despite missing out on a full-time race return for the 2017 season, Kallio would at least be rewarded for his testing efforts: a wildcard race entry was granted at the 2016 finale in Valencia, marking his first race back in the premier class since 2010. For the 2017 season, Kallio continued testing duties with KTM. The team initially handed the Finn two wildcard entries, at the German and Austrian rounds. Having narrowly missed out on a points finish at the Sachsenring, Mika produced an impressive display at KTM's home race in Austria, coming through the field to finish as the team's leading rider in 10th place, well ahead of teammate Bradley Smith. Not only was it the team's second top 10 finish of the season, but the result was also the first time a KTM bike had managed to finish a premier class race less than 20 seconds from the race winner. After his superb ride in Austria, KTM announced Kallio would be handed his third wildcard of the season at Aragon. Once more, the Finn produced a strong showing throughout the event. Having automatically qualified through into Q2 in 12th position as the fastest KTM, he would back up his qualifying efforts by coming home in 11th, just behind teammate Espargaro, but some 19 seconds ahead of Smith. After Aragon, the Finn was initially unsure whether he would receive any more race opportunities in 2017, but on 28 September, he was granted a fourth and final wildcard ride at the season finale in Valencia. Kallio's performances from his wildcard outings put him in contention for a possible full-time ride in place of Smith for 2018. However, on October 11th, KTM ended speculation surrounding their rider lineup, electing to keep Smith as the team's race rider for next season, with Kallio continuing his role as KTM's test rider, with plans for more wildcards. Kallio suffered a serious knee injury when racing as a scheduled wildcard entry at the Sachsenring, German round in July 2018, disrupting the KTM test programme. KTM was forced to contract Randy De Puniet as a replacement test rider for the remainder of 2018, and to end any further test-rider entries at races, being too risky for their future plans. KTM MotoGP