 Complete the following phrase:   and , by contrast, were lean years for the M12. The engine was generally regarded as the most powerful in F1 at the time, producing approximately in qualifying trim by 1985, and Piquet took nine pole positions in 1984 alone. However, the engines mechanical reliability and durability under full workload suffered severely, with engine blow-ups and turbo failures becoming common occurrences. Furthermore, with FISA imposing a maximum fuel limit of 220 litres per race re-fuelling was allowed in 1982 and 1983, the 4-cylinder BMW suffered from high fuel consumption which often led to drivers running out of fuel and continued to suffer from poor reliability. Consequently, Piquet scored only three wins - the 1984 Canadian and Detroit races, and the 