General Motors made an uncommon running update to its popular 2018 GMC Terrain and 2018 Chevrolet Equinox crossovers to bolster side-impact crash safety last year. The update, which consumers won't be able to spot by looking at the crossovers' exteriors, was applied to 2018 GMC Terrains built after Nov. 28, 2017 and 2018 Chevrolet Equinox...
