After the good results of the previous season, 1998 was a disaster for Prost. The AP01's main weakness was its gearbox: it was unreliable and heavy, which prevented the team from finishing races, upset the balance of the car and meant that the team could not optimise the position of its ballast, as many of its rivals could. It was Jarno Trulli who first identified the balance problems with the rear end of the car.