hydraulic valve lifters, longer-life valve stem seals that reduced oil consumption by 50%, and redesigned water pump, head gasket, and thermostat. Warranty was upgraded to five years or . In 1977 a pulse-air system was added to meet stricter 1977 U.S. exhaust emission regulations and the engine paint color (used on all Chevrolet engines) changed from orange to blue. In August 1975, Chevrolet conducted an endurance test of three Vegas powered by Dura-Built engines, advertised as a "60,000 miles in 60 days Durability Run". Supervised by the United States Auto Club, three pre-production 1976 hatchback coupes with manual transmissions and air conditioning were driven non-stop for in 60 days through the deserts of California and Nevada by nine drivers, covering a total of . With the sole failure a broken timing belt, Vega project engineer Bernie Ernest said GM felt "very comfortable with the warranty." Motor Trend said "Chevrolet chose the 349-mile Southwestern desert route in order to show the severely criticized engine and cooling system had been improved in the 1976 model." In ambient temperatures between and the cars lost of coolant (normal evaporation under the conditions) during the 180,000 miles. They averaged and used one quart of oil per 3,400 miles. Driving expenses averaged 2.17 cents per mile. One of the cars went on display at the 1976 New York Auto Show. The 1976 Vega was marketed as a durable and reliable car. Engine output summary notes: 1972–1977 hp/torque ratings are SAE net L-11 engine standard on 1977 models Stillborn engines OHC L-10 The optional L-11 engine was part of the Vega development program from December 1968, initially with a tall iron cylinder head that had an unusual tappet arrangement and side-flow combustion chambers. The Chevrolet engine group then designed an aluminum crossflow cylinder head with single central overhead camshaft, "hemi" combustion chambers, and big valves. This was lighter and about lower than the Vega production head. Although numerous prototypes were built and manufacturing tooling started, the engine did not receive production approval. It would have given higher performance than the iron-head engine, without its differential expansion head gasket problems. RC2-206 Wankel In November 1970, GM paid $50 million for initial licenses to produce the Wankel rotary engine. GM president Ed Cole projected its release in October 1973 as a 1974 Vega option. The General Motors Rotary Combustion Engine (GMRCE) had two rotors displacing , twin distributors and