I thought if you don't owe any taxes you lose the credit anyway, but I could be wrong on this.
if you don't owe any taxes, there's nothing to credit against - but you might get the money upfront anyway with a purchase in 2024.
as it works for 2023, when you file taxes for 2023 (in 2024), if you net owe greater than 7500, you can claim the full credit. if less, then only for the amount owed.
but you've waited many months, if not a year, before being able to realize the credit.
the same will apply in 2024, except as a PoS credit, you will PAY THE FEDS BACK for what you don't cover in taxes owed, in 2025 with your tax return filing.
So in that circumstance, if you owed tax of 5000 for 2024, you would be liable for payment of 2500 with your 2024 tax return (filed in 2025).
But you get the funds at point of sale, and pay the Feds back if you don't qualify for the full amount - after many months or a year after having spent the money.
All this assumes that the IRS is up to speed with their Forms, as well as their backoffice systems. Maybe not ....
Note that this year's tax filing season saw delays and confusion, with subsequent manufacturer messaging changes and car pricing adjustments all over the place.