On older cars here the tax on private sales is inexpensive, unless the car sold for over $15,000.
They used to be pretty loose on these sales, you’d fill out the paperwork and say you paid under $15,000 and all was good.
Now they take any reported sale under $15,000 to be a lie. Even buying a 4 door AMC Ambassador will have you receiving a letter from the state later saying they know you paid over $15,000 and now you owe tax and penalties. So it is very important to document the sale on both ends and have ironclad paperwork to prove you paid less than $15,000 on an older car or the state will screw you.