On the flip side, I pull the NADA used car values for my vehicles once a year or so, just to see where they stand.
I have a 2016 Ford F-350 King Ranch dually that I bought new in October, 2015. Sticker price on it at that time was $71k. I bought it for $60k (all kinds of incentives on expensive vehicles back then). I paid it off (a little early) last January.
This time last year, the NADA clean trade-in value with around 100k miles was right around $40k, clean retail was around $42k (diesel pickups hold value well).
Here are the numbers I just pulled (on a truck with 110k miles). Note that clean retail value is about $3,000 less than what I paid for it 5.5 years ago.