Normal sudoku rules apply. Digits in cages sum to the clue in the top left corner. Two race cars (blue and green) start in box 1 and race around the track to the chequered flag line in box 2 (in the 16 cage). Draw green and blue lines to show the paths that the cars take. Each checkpoint (cage) shows which cell each car passes through. The cars may not enter grey shaded cells, and must avoid all oil slicks (given digits). The paths cross exactly 3 times during the race. The paths do not share cells. Digits along the blue path have an equal sum N within each 3x3 box the path passes through. Adjacent digits along the green path must differ by at least 5.