Comment 1 for bug 1119454

Confirming it, but i'll expand on it a bit, because there are actually 2 issues at work here, one known already (i think).

For step 3: you can build 4 when 4 of those vehicles are deployed. If you undeploy one of them, you'll be able to queue 3. If you undeploy 2, you'll be able to queue 2. Undeploy 3, you can build only one. But If you'll undeploy all of them, you'll still be able to build one. That's because of the queuing issue the game has with building multiple units with BuildLimit. If not that, you'd be able to queue 5 units when 4 units exist and are all deployed.

But back to this issue, each time a unit with a BuildLimit is deployed into a structure, you'll be able to queue one more unit to bypass this limit. Deploy 2, you can now queue 2 more units! You built 2 new ones? Deploy them, you can build another 2! And then again. And again.

In the end, there's no limit to the amount of units you can build this way, as long as you careful not to have 5 of them undeployed (in their vehicle state) when a new one is produced.