High Way: If that is a Sudoku High Way, I shouldn't be Allowed to Drive!

Today's Puzzle:

Most difficult puzzle featured yet. I suspect I missed something in the solution path that made this far longer than it should have been.

Can you spot it?

Link to Play Along:

High Way by Mujika http://tinyurl.com/SudokuSleuthHighWay

Rules:

Normal sudoku rules apply. Cells that are a chess knight's move apart must not contain the same number Cells with grey squares must contain even numbers Numbers in cages sum to the number in the top left corner of the cage. Digits on an arrow must sum to the digit in the arrow's circle. Digits along the indicated diagonal must sum to the given total