First launched in 1978, the B7 Turbo Coupé/1 was Alpina’s first full conversion for the BMW 6 Series platform and featured a 300-brake-horsepower turbocharged variant of BMW’s inline six-cylinder engine sourced from the 630 CS, chassis code E24.

Additional improvements included an upgraded Bilstein suspension, ventilated brake discs, a body kit, and signature Alpina multi-spoke wheels.

While Alpina built 130 B7 Turbo Coupés upon BMW’s E24 6 Series chassis, just 20 of those were equipped with catalytic converters and designated the B7 Turbo Coupé/1 Katalysator.

These cars produce only 324 horsepower, compared to the 334-horsepower output of their non-catalyzed B7/1 siblings.

However, this exclusive 3.5-liter straight six-cylinder configuration offers a different driving experience entirely by generating more torque at lower engine speeds: 383 pound-feet at 2,400 rpm as opposed to 377 pound-feet at 3,000 rpm.

Furthermore, this model’s engine boasts a slightly lower compression ratio...