What is important in the this tread is if the 221 that is available at minute 3 (and not 223 that is not) has enough utility compared to the kubel to cost 10mp and 15 fuel more.
This is probably your best argument here. However, if you look at the stats and how you actually play with the 221 directly following its entry onto the field, the answer is pretty clearly: "yes". The unit is much more impactful at ranges closer than 30 than the kubelwagen is. Which synergizes with the fact that it has more health than the kubel does plus a rotating turret.
The 223 is also worthwhile even considering the extra cost in that it's the only OKW unit that can pay itself off. Granted this is over the course of 2-3 minutes. It's basically a gambit saying: "I will bully you in the early game, remain annoying a short while later, and then I'll recoup all the fuel I paid to do that in the first place, although my other light vehicles will come out slower."