Deductions & credits

I have more than the credit on liability to offset the credit. In schedule 3 shows a credit of only $1,243 for the car, not $4,502. the other thing that calls my attention is that after estimated payments of $5,196 I still show a tax due of $2,386 (without adding the car) and after I add it, my tax due goes down to $2,343. Am I getting only $43 of credit? Should I start all my taxes from the beginning?