Front impact
Lexus demonstrated to Euro NCAP that the knee airbags protected the front seat passengers' knees and femurs from injury in a wide range of seating positions. However, the brake pedal moved rearward by more than 100mm, posing some threat to the lower legs.

Side impact
The IS scored maximum points for its performance in the side impact and pole tests

Child-protection
The IS was awarded maximum points for the the protection it offered the 3 year old dummy in the frontal and side impacts and the 1½ year old lost only a fraction of a point. The front passenger airbag can be disabled to allow a rearward facing child restraint to be used in that seating position. Information presented to the driver about the status of the airbag was in English only but, otherwise, the system met Euro NCAP's requirements. The presence of ISOFIX anchorages in the rear outboard seats was not clearly marked.