Even if this is a hypothetical situation, I have to point out your errors.
If you assume a 25% margin in Q1, you have to apply the whole 25% to all the 4,750 vehicles sold. Not just the incremental 2,500 that you have calculated above. This is math 101.
There was no bloated inventory in Q4 2012. In the finance world, which you are not in, we use the term of bloated inventory to describe the situation of weak demand. In Q4 2012, the factory was running at record over time to produce cars to meet demand. Obviously, there was no bloated inventory to speak of. This is finance 101.