IPA: //ˈsaɪd.kɑːr//
KK: /ˈsaɪdˌkɑr/
A small vehicle that is attached to the side of a motorcycle, used for carrying a passenger or cargo.
He took his friend for a ride in the sidecar attached to his motorcycle.
Sidecar → The word is formed from "side" (from Old English "side", meaning the lateral part) and "car" (from Old French "carre", meaning a vehicle). A sidecar is a vehicle that is attached to the side of a motorcycle, thus literally meaning a car that is on the side.
Think of a 'lateral part' ('side') that is attached to a 'vehicle' ('car') — that's what a sidecar is, a vehicle that rides alongside another.
No commonly confused words.