Posting this information I found in regards to the above.

Wikipedia(JP): Girls und Panzer#Lingo

冬季無限軌道杯 (Winter Mugenkidou Cup)

最終章で開催されている戦車道の大会。日本戦車道連盟の設立を記念して発足した由緒ある大会で、開催が第40回以降途絶えていたが、プロリーグの翌年からの開幕を記念して20年ぶりに復活した。

A tankery competition held in The Final Chapter. A venerable competition that was established in commemoration of the creation of the Japanese Tankery League. Although it has not been held since the 40th National tourney, it is now being held for the first time in 20 years to celebrate the opening the professional league in the following year.