What was the first production Porsche to use a V8 engine?

The first production Porsche to use a V8 engine was the Porsche 928.

Porsche introduced the 928 in 1977, and it became the company’s first production car powered by a V8. The original engine was a water-cooled 4.5-liter unit mounted at the front, a major departure from the air-cooled, rear-engine layout associated with the 911. Power was sent to the rear wheels through a transaxle, helping the car achieve near-balanced front-to-rear weight distribution.

Porsche conceived the 928 as a comfortable grand tourer and, for a time, as a possible replacement for the 911. Its 2+2 seating, hatchback body, quiet cruising ability, and large V8 gave it a broader luxury-performance mission. The 928 won the 1978 European Car of the Year award, unusual recognition for a sports-oriented model.

Later versions received larger and more powerful V8s, including 4.7-liter, 5.0-liter, and 5.4-liter engines. Production continued until 1995. The Porsche 918 was a much later hybrid supercar, while the 944 used four-cylinder engines, so neither is the first-production-V8 answer.