I've found that the scale Hasbro goes by is more between 1/18th and 1/16th (1/17th?). I have a 1/18th scale Rubicon that is scarcely larger than a John Deere Gator in the same scale. When looking at vehicles - the die cast collector's cars for example - have two figures in mind, if not in hand to get a size perspective. I use file cards marked with the heights of a couple of figures (so as to not have the overly nosey think you're pocketing someone elses figures when in a store). While this won't help with useability later, it will let you know if the items can at least make good eye candy for back drops and scenery.

Bayer