The S40 has earned good crash-test scores from the Insurance Institute for Highway Safety. Specifically, it scores Good (the best possible) in frontal and rear impacts and Acceptable (one ranking below) in the side-impact test.

The wealth of standard safety features includes side-impact and side curtain airbags, all-disc antilock brakes, an electronic stability system with traction control and a tire pressure monitoring system. Advanced options include the Blind Spot Information System, which lights an indicator just inboard of either of the S40's side mirrors when a car occupies its corresponding blind spot.