Some well timed good news for General Motors as two of its midsize SUVs, the Chevy Equinox and GMC Terrain, aced a challenging "small overlap" test crash. The Mazda CX-9 and Honda Pilot were the worst performers. ABC News reports the small overlap test crash replicates what happens when the front corner on the driver's side slams into another vehicle or an object like a tree - at 40 miles an hour. The Insurance Institute for Highway Safety tested midsize SUVs and gave the highest rating of "good" to the Chevrolet Equinox and its twin, the GMC Terrain. The Institute's David Zuby says the Honda Pilot scored lowest, and had significant structural collapse, which contributed to the dummy's head sliding right off the driver airbag. The Toyota Highlander was the only other SUV passing the test, with a rating of "acceptable".