Agree, why
TrueCar is very handy for buying a new car/truck and
NADA is usually pretty good or a bit low about current real values.
Key is to buy right in the first place and in my case with the right timing & rebates I was able to buy a new GC with the V6 and towing package and 15 miles for just a few hundred than a 2011 with 10K miles. Then GCs became popular so the plant added more workers.
ps Have been towing with 6s since a '92 MiniVan replaced a V-8 stationwagon. My RV had a BMW turbo diesel and they are really nice but expensive in Florida & VVTi&e requires DOHC (or some really creative clockwork).
pps with direct injection & boost you can get close to diesel efficiency with 87 PON. That may be the next big thing.