Panzer Evolution

Sorry, but that's totally wrong. There were no linear evolution in german tanks. Panzer 4 wasn't the successor of Panzer 3, it was a parallel development. P3 was a medium battle tank. P4 a heavy support tank. Panzer 2 was a cheap substitute, because 3 and 4 weren't battle ready and neither the base for 3 nor 4. P5 was planned as a medium replacement for Panzer 3. P6 was an heavy assault tank and should replace 4. 

But as Panzer 5 wasn't ready as the heavy armored russian tanks showed up, they wanted to upgrade P3 with the long 75mm. This wasn't possible, because of the too narrow turret bearing, so P4 switched it's role to medium battle tank instead.

The Leopard 1 has nothing to do with german WW2 tanks, that evolution ended with the Maus and E-Class. It was based on Nato tanks, like the AMX 30 and even had a british gun. Then came the KPZ 70, that was a failed joint venture between germans and americans, and this was the base for the leopard 2 and the abrams.