9. NSU Ro80 (1967-1977)
Introduced in 1967, the NSU Ro80 was a technological marvel, showcasing sleek aerodynamic styling and pioneering the use of a rotary engine in mainstream vehicles. Its smooth, compact Wankel rotary powertrain offered exceptional refinement and performance, earning accolades and even the prestigious European Car of the Year award. However, despite its technical brilliance, the Ro80 struggled with persistent reliability problems, particularly premature engine wear and high oil consumption. These durability issues eroded consumer trust and burdened NSU with warranty costs. Ultimately, the innovative Ro80, though visionary, failed commercially, leading to NSU’s merger into Audi and marking the decline of rotary-engine ambitions.