I think you will be a happy camper -- tax liability is not the same as owing or being due a refund. If you have more than $7500 in tax liability for 2019 in the end (line 11 of your 1040), you can take the full credit. The EV credit goes into line 12 of the 1040 (via form 8936 and schedule 3), and offsets the tax on line 11. Line 13 is where the credit is partially or fully lost if your total tax liability wasn't at least $7500 (where it says if less than 0, put in 0).
The amount of tax that was withheld doesn't even get entered until line 16, and has nothing to do with whether you get the tax credit or not. The credit will of course result in paying less or getting a larger refund than you otherwise would have on April 15th.