for i in {a..c} ; do sudo smartctl -a /dev/sd$i | grep -i "SATA Version" ; done
SATA Version is: SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
SATA Version is: SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)