I bought my 2000 with lmpg of 54.7. It was sold in Alabama, sold again to Macon, Ga and had 33000 miles on it. I had never seen a citrus one before then, but it was absolutely perfect condition, so I bought it. I put a hot air intake on it, pumped the tires (Sumitomos) up and could get 70 on my commute. I did a tire test with Rick Reece, and found by going to the Bridgestones, I improved my mileage about 13mpg. After a couple of months, I learned to drive it, and am still learning little tricks. (I just hit 74.0 lmpg at 85000 miles. Most of it highway.)
If whoever had it drove it like their Chevy truck with the A/C on all the time in town and short trips with low tire pressures, I don't think it is that far out of line. It would also depend on terrain also.
Go over it with a fine tooth comb, paying very close attention to wear patterns on the tires, and general condition of the car, and you can learn alot. See if you can do a 20 or 30 mile test drive and see if you can improve on it. (that might be a little difficult to improve a bunch without some practice).
I am extremely happy with my car and am glad I bought it.