Cool RTS idea with just vehicle units! I would love to see a tutorial and tooltips describing each building and vehicle. Also I would consider adding an animation/circle to when a building is producing a unit and when the building dozer is working on building a building. I liked that the "gathering" vehicle started its route without having to be told and I liked how these trucks fired a set of rounds then had to reload. Great so far and I can't wait to see it flesh out. 
Viewing post in Bombs and Bullets jam comments
Everything you just said is planned. We are going to record a tutorial / intro video but I don't have the time and the game isn't solid enough for it yet. You can build infantry via the barracks, only a rifleman and driver though. In the far future, we plan on adding aircraft and ships as well.
There's other features buried in there that aren't immediately obvious. Like all vehicles having a driver that can get out, individual character portraits and names, infantry boarding into apcs, etc., Multiplayer via LAN technically works too.
It'll be much better in version 0.02, although but it'll be a few more versions than that before it's worthy of getting put into Early Access on Steam.