The “B” version of Panzer I tank was developed after realizing of the poor power performance of “A” version. The original Krupp 60 HP engine was thus replaced by a more powerful Maybach 100 HP one. Such change unavoidaby led to a hull enlargement so as to fit the new engine in. Only one fifth, more or less, of the total Panzer I tanks supplied by Germany were of this improved “B” version --that is, between 21 and 30 units.