Wow, such controversy Christopher has the right idea, a "gasser" has a certain toughness, and a definite "vibe". To those around drag racing in the 60's, a real gasser is immediately identifiable. While this is a neat car, it is NOT a gasser, and typical of what some people label as a gasser. It is a "highrider". That is what we called street cars like this in the 60's.
As has been said, traditional gassers were small, light coupes, originally made in the 40's, with ( usually ) big engines. I know there are exceptions, but the formula was normally the lightest body with the biggest engine. When NHRA changed the frame regulations from "original" to something else I cant remember, traditional gassers were dead. Mustangs and ' Cudas never had full frames, however the Malco Gasser is a great example of the change that led to the death of the original concept. The "El Padrone" Opel is also a good example of the crossover to a close cousin of the funny cars ( complete with turbo ) which changed the class. Maybe we should ask the Doc if he meant "traditional or vintage" versus "nostalgia" as they aint the same!