Remember in '91 during the Gulf War, gas went up a good amount for awhile, then came down cheap for a long time...so, not sure if that cost is based on those higher figures. [edit, I think you have a '92...not sure the details they used, but if you figure 15k miles a year and combined of 18 mpg, that would be ~$1.15 gallon)
It's funny to think that a CD player was still a pretty high tech ($) option in a car, back then; probably like a oem navigation system option. Of course, they often charge ridiculous figures for options like that, so I could believe it.
Curious to know how many came with CD players, anyway?