No no no no no no no no no no no no no no no. I don't know how many times we need to go over the same thing.
It has NOTHING to do with what you owe in April. It has everything to do with what your LIABILITY is.
Liability = what you owe the feds for the whole year
Withholdings = what you withhold from your paycheck (etc.) during the year
Tax time in April = Liability - Withholdings. If you withheld too much, you get a refund. If you didn't withhold enough, you owe uncle sam more money (and possibly a penalty).
The Tesla rebate is dependent on the liability. Not the withholdings. Nothing to do with April, except that's when Tax season ends.
For your case. A) correct
B) If your tax liability was more than $7,500, you'd get a check for $5,500 back
C) if you were due a refund in April, because your withholdings exceeded your liability (and your liability is more than $7,500). You'd get a check for $7,500+whatever you overpaid.