That's what it says, but I'm not entirely sure. Buick seems set in trimming their cars "CX", "CXL", and "Ultra." Why would they deviate from that to name one "CXS" unless it was supercharged? I wouldn't be surprised if the CX and CXL used the 215hp 3.8L with the 3.6L optional on the CXL and the CXS used the 260hp supercharged 3.8L.