Safety is a top priority at Volvo, and all S40 sedan and V50 wagon models come with side curtain and side-impact airbags, projector-type headlamps, a rear fog light, and anti-lock brakes with electronic brake-force distribution.

When Volvo re-engineered the S40 for 2004, the primary goal was to stuff the same levels of safety found in the flagship S80 luxury sedan into the S40's small package. To that end it was designed using something called VIVA, for Volvo Intelligent Vehicle Architecture. What appears to be an unprecedented amount of time, research, testing and detail went into the construction of the chassis and body in the interest of crash protection. There are several zones of deformation upon impact, built with different strengths of steel depending on that zone's function: conventional, high strength, extra high strength and ultra high strength steel.