I've been using my Garmin for a while in different cages. During a trip to Biloxi I noticed the speedometer and GPS were spot on so I'm fairly confident it's accurate. I'm a daily rider so I not only ride to work every day but on weekends I travel with the HOG group for breakfast runs. As you know Harley owners like to ride fast. I just know that with my V-star 1300, anytime I pushed 80 to keep up with 75mph highway traffic my fuel mileage tanked because I was pushing close to 4000 RPM. Besides as I stated before, it's Texas and everything is fast and towns are spread out in the west so fuel mileage is really important out here.