Seems like sellers are really overusing the term
investment grade. Every other car that goes up for sale is described as investment grade seemingly regardless of condition and mileage.
For example:
http://forums.pelicanparts.com/porsche-cars-sale/879422-1995-993-sunroof-coupe.html
83k miles on the clock, paintwork, and a far less than pristine interior wear - yet it's an "investment grade car that is going up in value daily." To me I consider a true investment grade car is one with super low mileage in mint condition that will be purchased with the intention of not driving it often. Once you are at 83k miles I would consider that a nice drivers car, but far from investment grade.
Am I thinking of the term correctly?