I heard the speedo was like 5mph slower than actual speed. Mine seemed to be within 3 mph accurate when riding along with another bike.
Excellent engineering is right on the XT and basically the same motor since the 1980s, just a bit refined with fuel injection, and at around 75 miles per gallon is really hard to beat. Extremely reliable. I will keep mine stock except for skid plate and a rear rack.
Try it with a gps. Mine is 5 mph off. Other than that I do like it for quick trips around town and some off roading once in a while.