My vote would be for just about any of the 70's era Monogram 1/24 scale car kits. Many of them are iconic and should be on this list. Some of the more iconic examples are the California Street Vette, any of their tri-five Chevys, and of course, the '69 Camaro.
The Camaro in particular is a "must build" in my opinion. Everyone has an opinion about this one, both good and bad. No, it's not the most accurate representation, but it is definitely a fun kit to put together, and in recent years it seems to have overcome a lot of the negative hype surrounding it and is starting to be respected and loved for what it is. A great nostalgia build. Love it or hate it, just build it and see for yourself.