I have the SpeedDRD set to 6.1% correction. The 238 indicated should be about 14 more or 252 miles if the ODO was on before I put the SpeedDRD on. I did have my windscreen (oversize) set to aggressive or more upright than normal.fredz43 said:Also, in my GPS checks for speed and highway mileage marker checks for miles, I agree with the 6% correction for speed, maybe a bit more, but mileage checks have only looked like 2% correction. You may have gone further than 238 miles.