The speedometer gets it's information from the ABS system. If the ABS is not in alarm, the problem is probably the instrument cluster. I replaced mine about 3 years ago because it wouldn't go over 35 mph and the turbo guage didn't work. I see them frequently on eBay for $50 or so.
As far as the fuel guage goes, look at the DTE in the SID. If it shows an accurate mpg reading, the fuel level sensor in the tank is probably good, and the problem is in the instrumemt cluster... Ron