The 1978 Monza line expanded to include rebadged holdovers from the Vega line, which ended production after the 1977 model year. Chevy grafted a new Monza front end onto the previous Vega hatchback and wagon body-styles. The Monza "S", marketed as the Monza price leader, used the Vega hatchback body. With production of only 2,000 units, it was speculated that this was simply an effort to use up a stock of leftover 1977 Vega bodies. The Monza wagon was also offered in an estate wood-trimmed version, using the Vega wagon body. The 1978 Monza line gained a new base coupe and 2+2 hatchback with round headlights in an upright front end with a crossbar grille and new tri-colored taillamps. The base 2+2 hatchback also used a new blunt rear taillamp panel incorporating the license plate mount and a conventional rear bumper. The new Monza Sport series was offered in both 2+2 hatchback and notchback body styles, using a modified version of the previous quad rectangular headlamps, now above a full-width open-slot grill. The 2.5 liter (151 CID) inline-four "Iron Duke" was standard for 1978, replacing the Vega's inline-four engine. Engine options were a Buick-designed 3.2 liter (196 CID) V6 engine with a two-barrel carburetor that produced at 3,600 rpm. Replacing the 3.2 liter V6 in California and high-altitude areas was Buick's 3.8 liter (231 CID) V6 engine. Four-cylinder engines and the 3.2 liter V6 were not available in high-altitude areas. The 305 cubic-inch V8 remained optional in all but the "S" hatchback and wagon models. Discontinued at the end of the 1978 model year were the S hatchback, Towne Coupe sport option and the estate version of the wagon.