Demon 340 is the muscle Demon — the 1971-72 A-body fastback with the 340 LA-series small-block four-barrel as the standard engine. Distinguishing equipment included the matte-black performance hood with twin functional scoops, Rallye instrument cluster, heavy-duty suspension, and Demon 340 graphics on the body sides and decklid.
The 340 four-barrel rated 275 horsepower gross in 1971; the 1972 net rating was 240 horsepower (the rating system changed mid-1971). Same engine across both years; only the published number differs.
Production: roughly 10,000 cars across 1971–72. The Demon 340 was Dodge's answer to the Plymouth Duster 340, which preceded it by one year and outsold it considerably in the high-perf A-body segment.