Your income just has to be under the max, there is no minimum income. But you must have a tax liability on your 1040 line 22. It's not whether you get a refund or a tax due. And the withholding doesn't matter. It's if you have a tax liability on your income. Look at your 1040 line 22 for total tax. So as long as Line 22 is more than $7500 (before applying the credit), you'll get the whole credit back.
Basically you can only reduce the TAX on line 22 to ZERO. Then you just get back all your withholding, not any more. So you might want to increase your income so you can use all of the credit. Like convert a traditional IRA to a ROTH IRA or sell some stocks with a gain.
See IRS EV Credit for new vehicles purchased in 2023
https://www.irs.gov/credits-deductions/credits-for-new-clean-vehicles-purchased-in-2023-or-after
