 The cars had an aluminium @-@ alloy double @-@ skinned construction , and were delivered unpainted to save time . A red adhesive strip ran through the length of the cars in the middle to match the operator 's visual branding . The unpainted cars had a shiny appearance upon delivery , but as dirt and grime accumulated it became a recurring problem for the operator and attracted several public complaints . In response , MRT Corporation built a wash machine at Bishan Depot in an attempt to clean up the cars ' exterior proper . After refurbishment , the problem was solved by covering the cars ' exterior entirely with giant stickers , creating a livery that is similar to the newer C751B and C151A rolling stocks . 
