Anyhow, if the Jeep is coming out this early and is causing these problems, then it should be looked at. The M3 rush gameplay was cheesy and shitty as fuck, if it's being replicated it should be stamped out. I haven't managed to use it, only see it second hand, so I can't have an informed opinion on this matter other than what I've read/seen.
You can't spam them the same way, and they're not nearly as mobile. Frankly, they're just about the same as the actual M3 is right now; clearly, no faust means OKW struggle with both.
The time between first M3 and first Dodge is pretty much no difference, though. Dodge mounts tougher squads, M3's are a lot more mobile (and a smidge more durable).
Every subsequent unit takes longer than every next M3. They're 240/20 rather than 190/15, after all.
They also can't mount flamers, but can invest in BARs instead- these take longer to get, but not by much.
Frankly, they're the exact same thing in US paint jobs.
The only real davantage the dodge has is it can pop the crew out, patch up faust damage and flee. But any decent M3 use has combat engineers to do the exact same thing.
For your extra cost, you get a rifle squad to defend your emergency repair crew, and can keep your vetted crew for a later vehicle if you so desire.