Your comment reminded me of an incident with a school chum of mine, who had a very expensive custom paint job on one of his cars.
Some lady in a grocery store parking lot misjudged her turn into the parking space and mangled the side of his car. Not just one small dent, she kept going scraping the side of his car from just in front of the back wheel, all the way up to only an inch behind the front of the passenger doors front edge.
Wasn't exactly hit and run, but she backed back out and moved down three or four more parking spaces. Those who saw it happen wrote down her and his license plate numbers and went inside to have him paged.
Her insurance company, State Farm, tried to get out of paying for the repairs to his car in several ways.
Their first stunt was saying they were only libel for paying to restore the damaged area of the car to factory condition. This is not true!
When that didn't work, next they said they were going to total the car and pay him blue book, and he could buy the car back back as salvage. Blue book on his car was only 250 bucks. However, he had just had the car appraised after the work was done to it, so he could insure it for the replacement value. State Farm then changed their mind, they didn't want to pay the documented appraised value of the car by totaling it.
He took his car to several shops to find out what it would cost to repair the damage, first only to factory primer condition, then to the custom shops to see what it would cost to duplicate his custom paint job. These he gave to State Farm to cough up the dough. They still refused, so he gave his papers to an attorney, figuring the attorney would just draft a letter of intent to sue, and State Farm would then settle.
Nope, they still refused, so the attorney took them to court.
State Farm should have settled, because after the dust settled, they not only had to pay to have his car restored to the condition it was when it was hit, they also had to pay his attorney fees, court costs, and the cost of rental car from the day it was hit until the day it would be delivered after repairs, even though the guy did not need a rental car as he had other cars to use. The payments were court ordered, so the insurance company had to pay them, hi hi...
A cars blue book value rarely if ever holds up, even if you don't have a documented appraisal.
This old hogwash of normal maintenance does not add value to a car was shot down years ago.
Replacing an old motor with a new one is NOT normal maintenance, it is an upgrade to the vehicles value.
Essentially, you have changed the 13,000 per year mileage deduction, back to zero miles with the new motor, although that is only one aspect of the overall rating. You would have to replace the entire drive train to get the mileage deduction back close to zero.
Liability insurance is to pay for the damage caused by the liability insurance holder. That damage cannot be determined from a fixed rate book, nor negated due to averages of other similar items. But insurance companies try to use these methods to keep from paying out what they should be paying out.
It shouldn't matter if you have a 1,000 dollar car or a 50,000 dollar car. If you just put 2,000 dollar tires and wheels on your car, and someone slams into one breaking it. They should be libel for replacing that tire and wheel. They would be if it was sitting on a shelf in front of the store. So why not if it is affixed to a car? The blue book value of the car should have nothing to do with replacing the damaged tire and wheel. But insurance companies are always trying to screw the person who's property was damaged by their client.