uses Bosch Motronic 1.1 engine management. In 1987, a catalyzed model with Motronic 1.3 engine management was introduced. The compression ratio was reduced to 8.8:1 but thanks to the more sophisticated electronics power remained nearly as before, at . The uncatalyzed engine was kept in production for Southern Europe and other markets where unleaded petrol was not regularly available. Applications: 1985–1993 E30 3 Series 325i 1989–1990 E34 5 Series 525i 1988–1991 Z1 M20B27 The M20B27 was designed for efficiency (thus the e for the Greek letter eta in 325e) and low-rev torque. This is an unusual design strategy for a BMW straight-six engine, which are usually designed for power at high RPM. Compared with the M20B25, the stroke is increased from , resulting in a capacity of . Since many markets tax cars based on engine displacement, the eta's larger displacement meant that it was not suitable for all markets. It was expressly developed with the American market in mind. As per the M20B25, the bore is . To reduce friction and improve efficiency, the M20B27 changes include using the '200' version of the head (which has smaller ports), a different camshaft, four camshaft journals and softer valve springs. Due to these changes the rev limit on the M20B27 was reduced to 4,800 rpm. The initial version, called the M20B27ME, produces and at 3,250 rpm for models without a catalytic converter. Models with a catalytic converter produce and . In the United States, BMW's corporate average fuel economy was at risk of not meeting requirements by 1984, primarily due to higher sales of their bigger, more expensive cars in the early 1980s. The first car to use the M20B27 was the US market 528e in 1982. The compression ratio of the U.S. M20B27ME version was 9.0:1, compared with for cars sold elsewhere 11.0:1. In 1985, the M20B27ME.E version was introduced, increasing power output to despite a lower compression ratio of 10.3:1. In late 1987, the fuel injection was upgraded to Motronic 1.3 on the US market plastic bumper 325e and 528e 'Super Eta', the cylinder head changed to the "885" version, the compression ratio was reduced to 8.5:1 and the redline increased to 5,200 rpm. Power output increased to at 4,800 rpm. In the early 1990s BMW South Africa used components from the Alpina C3 2.7 to produce an E30 specifically for Stannic Group N production car racing. The first