Williams technical director Sam Michael says the team still has a long way to go despite taking its best finish of the season in Valencia.

Rubens Barrichello took a strong fourth place having started from ninth on the grid, although team-mate Nico Hulkenberg was forced to retire with a cracked exhaust that the team is still investigating.

While pleased with a strong showing in Spain, Michael admitted however that the team still had plenty of work to do if it was to fight towards the front on a regular basis.

"Both drivers did well," Michael said. "Nico stepped up his game in qualifying and that was good to see. Rubens delivered strongly in the race and made the very best of what he had at his disposal.

"The improved performance of FW32 was due to the whole car package, and perhaps the specific nature of the Valencia circuit that suited our car characteristics. While we are heading in the right good direction, we and our partners still have plenty more work to do."

Michael also explained why the blown rear wing had only been fitted onto Barrichello's car for the race weekend and praised Cosworth for continued work to improve the engine fitted to the FW32.

"We had an installation issue with Nico's seat, but we'll have that sorted out for Silverstone," he said. "That said, the blown rear wing is still an R&D item, so it suited the team to have the cars split in Valencia. Given that we had some issues with the component during the race on Rubens car, it was the right call.

"As well as some other teams, we fitted new engines to both cars for the European Grand Prix. Cosworth are still on a rising curve with the engine and they've been working hard to find improvements within the engine homologation regulations. They are making good progress."