3
6 x x x x 1 9 x x
x 8 x x 3 x x x x
x x 1 7 x x x x 2
x x 2 x x x x x 7
x 5 x x x x x 1 x
4 x x x x x 3 x x
3 x x x x 9 6 x x
x x x x 4 x x 8 x
x x 8 2 x x x x 5

<http://forum.enjoysudoku.com/fluid-drive-tarek-s-1-t4995.html>

Solved with Grid66. Time 47 ms.
6 7 5 ║ 4 2 1 ║ 9 3 8 
2 8 4 ║ 9 3 5 ║ 1 7 6 
9 3 1 ║ 7 8 6 ║ 4 5 2 
══════╬═══════╬══════
8 9 2 ║ 3 1 4 ║ 5 6 7 
7 5 3 ║ 6 9 2 ║ 8 1 4 
4 1 6 ║ 5 7 8 ║ 3 2 9 
══════╬═══════╬══════
3 2 7 ║ 8 5 9 ║ 6 4 1 
5 6 9 ║ 1 4 7 ║ 2 8 3 
1 4 8 ║ 2 6 3 ║ 7 9 5