MITSUBISHI MOTORS made the most of their knowledge acquired from rallies around the world to develop the LANCER WRC04, as well as utilizing the capabilities of its bases in Japan and Europe. However, the innovative body design was carried out mainly by MITSUBISHI MOTORS' WRC development base, MMSP Ltd., in Rugby (UK). Mario Fornaris (Italy), the technical director of MMSP Ltd. commented that they would face the challenges of that new year without incorporating very complex mechanisms that generate many uncertainties from the start, but would stick to their policy of improving the car step by step and increasing its competitiveness towards the second half of the season. The engine fitted was the 4G63 model. The turbocharger and the intake and exhaust manifold were drastically changed. In addition, the work focused on weight reduction of internal parts with the aim of improving the response. The electronic control system was changed to another one manufactured by Magneti Marelli, and, by integrating it with the chassis control unit, weight reduction was achieved while also ensuring reliability. With Gilles Panizzi spearheading the team, three young drivers, Kristian Sohlberg (Finland), Daniel Solà (Spain) and Gianluigi Galli (Italy), took turns at the wheel of the second car in each rally.

Panizzi finished sixth in the opening Monte Carlo Rally. He got off to a good start, scoring points in his first race back in the WRC. However, after that, the team struggled with persistent issues and accidents. Even under such circumstances, Panizzi never gave up and managed to set three fastest times, including his stage win in Monte Carlo. The team was able to gather a lot of data from those races. In the middle of the season (July), MITSUBISHI MOTORS announced a partial review of their 2004 WRC activities. They announced that, after the end of round ten, Rally Germany, they would forego the rest of the 2004 season from round eleven, Rally Japan, and focus all their efforts on the development and testing of the LANCER WRC. At the end of October, they entered the 15th round, Rally Spain (Catalunya), as a test race. Panizzi and Solà defended the colors of MITSUBISHI MOTORS, while Galli flew the flag for the local RALLIART Italy team, all of them driving a LANCER WRC04. In this rally, all three cars completed the race, with Solà finishing sixth and Galli seventh, clearly demonstrating the vehicle's steady evolution.