I don't think anyone has advocated buying a phone to use as a car GPS.
The fact of the matter is that if one already owns a phone then that becomes an option!
To concern yourself with replacement cost is not germane to a GPS discussion if you already have a phone, unless you attach an additional risk due to use in your car
The Data use and cost for my two Apps in my car are not even noticeable
My car is a 2015 Honda Odyssey Elite with NAV. I never use that NAV, and regret having paid for it. I suspect if I did not have the cell phone, I'd go back to my Garmin NUVI.
YMMV