Panzer IV F is 40 ENY? What the hell, HTC? The M8 is ENY 35, but the Panzer IVF is ENY 40. Really, Panzer IV F should be 30 or 35. SdKfz 251/22 should be between ENY 35 and 40 (since it would be the easiest dedicated-AT platform to knock out in the entire game)
M8 has speed, which is a factor the same reason the M18 is 1 perk, extremely fast with a decent gun on it, the ENY is based on play ability and balance. Even at 40 eny the M8 will make no difference in the main arena, however if you take HE rounds, you can get to an airfield in under 4-5 minutes and de-ack it from a ranged positioned, where it takes 20-25 minutes in a Panzer F.
Panzer F is two different panzer Models, one version is Early war (L/24) and second is Medium War (L/43).
You gotta look at it in terms of perks, if a PzF knocks out a PzH he gets 3 perks per kill, you know how fast a tank can rack up perks, if someone gets 9 kills which is 18 perks and lands (at modifier 1.00) he has enough for a panther when its usually 17-18 perks.
You can rack up perks far to easily in ground vehicles, then again the drawback is you can lose them just as fast as well.
In the case of the SdKfz 251/22, I can see it being around or under 30 eny - again in terms of play balance, the Sdkfz is a very SMALL target - with a decent gun on it no less (L/46) and does 32mph, you simply lose the armor and it doesn't carry many shells - its a trade in play balance.
I'm of course guessing, HTC makes the final call on the eny system, but think of what happens if they add the PUMA, it would easily be 20 or 25 eny.