it from the 318i), because the 320/6 was never certified for sale there. 1981 The economy model 315 was introduced as a reaction to the second "oil crisis" in late 1979. More spartan than the other E21 models, it was the last E21 to be built and produced alongside the early E30 models. Baur TopCabriolet A cabriolet conversion was offered by Karosserie Baur, called the TopCabriolet. It consisted of a targa roof and an independent rear soft-top. The targa roof section was designed to fit in the trunk, while the boot cover doubled as a cover for the plastic rear windshield, protecting it from scratches and frost in winter. Production of the TopCabriolet began in 1978 and all engine options were available. The cars were sold via the BMW dealership network and all Baur models included the BMW warranty. A total of 4,595 vehicles were manufactured before production ended in 1981. North American models The E21 was sold in the United States from model years 1977 to 1983, first as the four-cylinder 320i, and from 1980 as the 1.8 liter 320is. Six-cylinder models were not sold in America, because the E21 versions of the M20 engine did not meet U.S. emissions regulations at the time. The 320i models sold in the United States have a thermal reactor as a pollution control device. U.S. models came standard with air conditioning. From 1977 to 1979, the U.S. models were powered by a fuel-injected version of the M10 four-cylinder engine. In August 1979, from the 1980 model year, the 320is model was released, powered by a downsized version of the M10 four-cylinder engine. This resulted in a acceleration time of 11.1 seconds and a top speed of . Just 2,500 320is's were produced. Due to American regulations, the following changes were required: larger front and rear "diving board" bumper bars, which increased the car's overall length by to . sealed beam headlights, larger indicator lights and side reflectors speedometer in miles-per-hour fuel gauge markings changed from litres to "full, ½, reserve" a detuned version of the M10 engine, initially using a thermal reactor to control exhaust emissions in 1980, the engine was downsized from 2.0 L to 1.8 L and the thermal reactor was replaced with a catalytic converter. The optional "S Package" sacrificed the factory air conditioning, but offered Recaro sport seats, upgraded suspension in the form of a rear anti-roll bar