Washing it, vacuuming it out and getting it running (at least starting) would help tremendously also.
I know I wouldn't buy a car based on somebody saying it ran fine 5 years ago, and if I did it would be a very good bargaining issue to buy it even cheaper. Having someone come out to look at the cleaned up car and being able to fire it up increases your selling power. Also listing an asking price helps, just saying you have 40K invested will scare most buyers away. Make them feel they are getting a deal and it will sell. Trying to sell a car that looks like its been sitting neglected in a field for 5 years and wont start just loses peoples interest.
Also, Pontiac (GM) never put a 1.8L engine in a Fiero, I dont even think they made one. I think the 4 cylinder engines were a 2.4L and the v6's were 2.8L.