Okay, so this manga clearly doesn't get as much attention as it deserves, so let's try to improve the situation a little. If you watched the original show, you know that before Germans gave every crew member radio, commander were just kicking driver's shoulders to tell him when to turn. So in this manga two girls ride small 2-crew tank, and the commander/shooter (Shizuku) rubs driver's (Rin) back to steer the tank. But unlike Russian tank commander, her nimble feet are bare. And through this foot-fetish adventure girls get more intimate and strive to win in unofficial light tank competitions for Senshadou rejects.
probably already decided if you should read it or not, but there are still a couple of things I want to talk about.
In terms of artwork 2 things caught my attention. Facial expressions are pretty good, like you can feel Kei's unease when she thinks about Alisa's winning chances that should be obvious; or Shizuku's smile after a fight, that goes from putting up a face for Rin to genuine happiness of resolution.
Secondly, legs. Shizuku wears black pantyhose over legs that Rin describes as "slim and beautiful". They doesn't get much thicker as you go from knees to hips and even her jacket wraps her thin body very tightly, accentuating her surprisingly decent-sized chest. Now Rin's legs have more meat on them, so she has the opposite body type, nice and soft.
The "princess" Shizuka herself may appear stoic, but is very passionate during battles (both tank and word fights). Her maniacal smile is invoked by admired images of horse-riding warriors of Sengoku era. Ever imagined yourself as a samurai fighting ninjas on top of cars while listening to anime music in a bus? I've only read 4 chapters, so I can't say that much about Rin, but she appears to be more of a "normal" girl to play off Shizuku's chuunibyou. She is pretty submissive and sees a dream in which her comrade rides her like a horse into battle. And there are lots of cameos from GuP characters.
Also, Rin wanted to try tanks after Nishizumi Miho "became a legend". This is as far as I know the only spin-off that actually takes place after GuP, so you can learn a lot of interesting stuff. Some of you fellow GuP fans probably disregarded this manga because the sport here is not strictly speaking Senshadou, but don't worry - battles are engaging and small tanks are very cute.
Yeah, this manga is super fun (sorry for using pointless buzzword, but since I actually described why it's engaging, I give myself a pass). If you are Girls und Panzer fan or foot-fetishist with yuri tendencies, definitely give this a try.