Here is an example of how I see using such a generic number.
I am looking for a new car. All of the cars I am looking at have about a $500 per month payment.
I have figure out my budget so that I $4000 in my budget to operate my car while driving 15,000 miles per year (after making the payment). Below would be the estimates provided of the cars that I have been looking at as prospects.
Car A cost $3500 to operate for 15,000 miles per year.
Car B cost $3200 to operate for 15,000 miles per year.
Car C cost $3700 to operate for 15,000 miles per year.
Car D cost $3900 to operate for 15,000 miles per year. .
Car E cost $4500 to operate for 15,000 miles per year.
Car F cost $4200 to operate for 15,000 miles per year.
I would eliminate cars E and F because they are outside my budget. I would probably eliminate D because it is a little close for comfort. I would then call my insurance agent and get detailed figures for Cars A, B and C from my insurance agent. I would also check out Consumer Reports for reliability history.
If I find that my insurance rates are substantially lower than expected making the other cars more affordable I may reconsider them. I just see this figure I suggest as a useful tool for ball park comparison.
But the problem is we don’t know how you relate to their estimates. How much of car A’s 3500 is insurance and how much better or worse would your insurance rate be compared to their estimate? How much of car B’s 3200 is it mechanical maintenance and how does you mechanic compare? If it turns out $2000 of A is insurance and your rates would make it $1000 and $2000 of B is maintenance and you’ll be taking it to them so that number is spot on then A is actually cheaper for you and their numbers did nothing other than steer you wrong.
That’s what I keep telling you, if they put numbers like that on the sticker they’d be FICTION, made up, having little if any bearing on you me or any other prospective buyer. Best to leave them off, since they’d be 100% meaningless junk numbers anyway. And worse each dealer would be using different standards for their math, so whatever “correction” you’ve figured out at one place doesn’t apply at the other. They wouldn’t be a suggestion, tool or ballpark; they’d be made up, useless and pointless.