While the 126C4's engine was powerful at around in qualifying making it virtually the equal of the BMW and Renault engines (and more power than McLaren had with their TAG-Porsche engines), the car itself produced little downforce compared to its main rivals with both Alboreto and Arnoux claiming all season that the car lacked grip. This also had an effect on the cars' top speeds at circuits such as Kyalami, Hockenheim and Monza as the cars were forced to run with as much wing as possible in order to have grip. This was shown in Round 2 in South Africa (Kyalami) where the Ferraris were some slower on the long straight than the BMW powered Brabhams, primarily due to the increased drag from high wing settings. The high wing settings also hurt fuel consumption during races with both drivers often having to drive slower than possible in order to finish races (re-fuelling was banned in 1984 and cars were restricted to just 220 litres per race).