Engine spark plug locations (R4) on Smart 450/451/452/454 petrol engine, view from above with intake manifold and intake hose visible.

Black and white photo showing four spark plugs labeled R4 mounted on engine cylinder head.

View full-size image ↗

See all Powertrain figures for the Fortwo (450), or browse the full figure library. Part numbers and callouts are community-sourced and cross-referenced against the manuals — confirm with your VIN before ordering.