Having tested it at 10 fuel awhile back at 0cp, it's definitely not a good idea as you end up with a situation where you can effectively fight it in the first few minutes. If it goes down it price it should go up in CP and be given abilities to allow it to scale into the mid-late game. Or it takes longer to call more trucks in.
Maybe OKW can deal with it as they have raketens, but Ostheer trying to deal with 2 dodge trucks with a rifle riding onboard on the cut-off in the first minute or so of the game that can shuffle in and out for repairs is very difficult to deal with and this is the time when your 3rd Grenadier squad arrives and you may only have the munitions for one faust.
I feel like a 1cp 15 fuel WC-51 with changes to its pathfinding (possibly acceleration) wouldn't be bad. I could definitely see it shutting down OKW but with the pfaus change it might be mitigated.