Complex sentence: Until some time after World War II, most high-end motorcar manufacturers like Bentley and Rolls-Royce did not supply complete cars but sold a (rolling) chassis, near-complete from the instrument panel forward.
Split into simpler sentences: Until some time after World War II, most high-end motorcar manufacturers like Bentley and Rolls-Royce did not supply complete cars. They sold rolling chassis, near-complete from the instrument panel forward.