I ran another 4 miles last night. The CardioTrainer was surprisingly accurate. I ran 4.06 miles in 39:20 (9:40 pace). 1st mile: 8:44, 2nd mile: 9:31, 3rd mile: 9:55 and 4th mile: 10:20. I think I started off too fast and paid for it in the end. All and all it was an effortless jog though.