We don't have to stop people from profiteering from this scheme. We have to make them realise that this will be their one and only 'cheap' car in their lifetime. Yes, they can profit from it (instead of the profits going into the gahmen's coffers), but their next car(s) wil never be at such good price anymore.
This may achieve a few things:
1) potential first-time buyer will consider hard before diving into their first purchase. Perhaps this may space out demand.
2) potential first-time buyer will consider hard before profiteering.
3) transfer the wealth from the rich to the poorer. i.e., the wealthier may go into the secondary market to buy out the right to first time car-ownership