Low mileage '92 gulping gas. Suggestions?

[Reks]

I recently bough a '92 240sx that has only 38k miles on it. It had one owner and she apparently didn't drive it much. I feel like I can practically see the needle drop on the gas gauge as I'm driving. I put some fuel injector cleaner fuel additive in the tank and am considering a new cold air intake. Could the problem just be from how little it's been driven? Will the mpg improve with some regular use? Any comments or suggestions would be much appreciated!