Front offset test: between two vehicles of the same weight, each going just less than 40 mph. Test results can be compared only among vehicles of similar weight.
Side impact: The test configuration resulting from this research is a 31 mph (50 km/h) perpendicular impact into the driver side of a passenger vehicle.
(the above info was copied from http://www.iihs.org/ratings/default.aspx)
By the way, how often can you control the speed of another driver? On US highway? Below 40 mph?